Planetary Gear Train for Automatic Transmission with 11 Speed Stages
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Solution Overview
Problem
Automatic transmissions with increased shift stages face challenges in installability, power flow efficiency, and production cost due to the increased number of parts, which also affects fuel consumption and drivability.
Innovation Solution
A planetary gear train design that achieves eleven forward speeds and one reverse speed using a minimal number of parts by incorporating four planetary gear sets and seven control elements, including clutches and brakes, to improve power delivery and fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the number of speed stages is increased to enhance fuel consumption and drivability, then fuel efficiency and drivability are improved, but the number of parts increases which deteriorates installability and power flow efficiency
Solution Approach 1:
The patent merges multiple planetary gear sets into a unified structure where gear sets share common components such as the carrier and ring gear. This integration allows the transmission to achieve eleven forward speed stages without proportionally increasing the total number of parts, as shared components reduce the overall part count while maintaining the multi-stage gear reduction capability needed for fuel efficiency.
Solution Approach 2:
The planetary gear sets are designed with multi-functional elements that serve multiple purposes. For example, the carrier and ring gear are shared across different gear sets, allowing these components to participate in multiple gear ratio configurations. This universality enables the system to achieve complex multi-stage transmission ratios without requiring separate dedicated components for each stage, thereby improving fuel consumption performance without linearly increasing part count.
2Use of energy by moving object
If the number of speed stages is increased to enhance fuel consumption, then fuel efficiency is improved, but installability deteriorates due to increased number of parts
Solution Approach 1:
The patent combines multiple planetary gear sets into a compact integrated assembly where components are shared across gear sets. This merging reduces the overall size and complexity of the transmission unit, making it more installable in vehicle configurations while maintaining the eleven forward speed stages necessary for optimal fuel consumption across different driving conditions.
3Use of energy by moving object
If the number of speed stages is increased to enhance fuel consumption, then fuel efficiency is improved, but power flow efficiency deteriorates due to increased number of parts
Solution Approach 1:
The integrated planetary gear set design reduces the number of power transmission paths and connection points between components. By sharing carriers and ring gears across multiple gear sets, the patent minimizes the number of meshing interfaces and potential energy loss points, thereby maintaining high power flow efficiency despite achieving eleven forward speed stages for optimal fuel consumption.
4Adaptability or versatility
If three to four planetary gear sets and five to six control elements are used to achieve eight or more shift stages, then more shift stages are achieved, but the transmission becomes lengthy which deteriorates installability
Solution Approach 1:
The patent merges planetary gear sets into a compact arrangement where components are shared, significantly reducing the axial length and overall size of the transmission. This integration allows achieving eleven forward speed stages with a more compact structure that is easier to install in vehicle configurations compared to traditional designs using separate gear sets.
Solution Approach 2:
The planetary gear sets are arranged in a nested configuration where inner gear sets are positioned within or adjacent to outer gear sets, sharing common components. This nesting approach compactly packs multiple gear stages into a smaller volume, reducing the transmission's length and improving installability while maintaining the required number of shift stages for versatile vehicle operation.
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
The design enhances driving stability and engine efficiency while reducing fuel consumption by optimizing the number of parts, improving power delivery performance and achieving multiple speed stages suitable for low engine rotation speeds.
Implementation Method 1
a first planetary gear set including first, second, and third rotation elements, a second planetary gear set including fourth, fifth, and sixth rotation elements, a third planetary gear set including seventh, eighth, and ninth rotation elements, and a fourth planetary gear set including tenth, eleventh, and twelfth rotation elements
Data Source
AI summary
A planetary gear train of claim of an automatic transmission for a vehicle may include an input shaft for receiving an engine torque, an output shaft for outputting a shifted torque, a first planetary gear set, a second planetary gear set, a third planetary gear set, a fourth planetary gear set, a first shaft, a second shaft, a third shaft, a fourth shaft directly connected with a transmission housing, a fifth shaft selectively connectable with the second shaft, a sixth shaft directly connected with the output shaft, a seventh shaft, an eighth shaft selectively connectable with the first shaft and the second shaft, and directly connected with the input shaft, and a ninth shaft selectively connectable with the sixth shaft.