Automatic Transmission Powertrain with Three Planetary Gear Sets
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Solution Overview
Problem
Existing automatic transmissions face challenges in achieving a high number of shift speeds without increasing complexity, durability, and efficiency, while manual transmissions with many speeds are inconvenient for drivers.
Innovation Solution
A powertrain configuration that combines three simple planetary gear sets and six frictional elements to enable eight forward speeds and two reverse speeds, optimizing gear train design for improved performance and fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of planetary gear sets is increased to achieve more shift speeds, then the transmission can provide more forward and reverse speeds, but the device complexity increases
Solution Approach 1:
Each planetary gear set is designed with multiple operating members that can serve different functions across various speed ranges. The first planetary gear set has operating members that can be selectively connected to achieve different gear ratios, allowing the same component to fulfill multiple roles in the transmission system.
Solution Approach 2:
The transmission is divided into three separate planetary gear sets, each handling specific speed ranges or functions. This segmentation allows independent optimization of each gear set while maintaining overall system compactness and reducing the complexity that would arise from a single large gear train.
2Adaptability or versatility
If the number of frictional elements is increased to control more gear combinations, then more shift speeds can be achieved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
Each frictional element is designed to perform multiple functions across different operating conditions. For example, the first frictional element can engage different operating members of the first planetary gear set to achieve various forward speeds and reverse speeds, maximizing the utility of each frictional element.
Solution Approach 2:
The patent combines multiple control functions into fewer frictional elements by designing the planetary gear sets with shared operating members. This merging reduces the total number of frictional elements needed compared to traditional designs where each gear combination would require a separate control element.
3Loss of energy
If more planetary gear sets are added to improve power transmission efficiency, then fuel consumption decreases, but the size and weight of the transmission increase
Solution Approach 1:
The three planetary gear sets are arranged in a nested or compact configuration where components of one gear set can be positioned within or adjacent to components of other gear sets. This nesting minimizes the overall volume occupied by the transmission while maintaining the benefits of multiple gear sets for improved power transmission efficiency.
4Loss of energy
If the gear train is designed with more operating members to enable more speeds, then fuel mileage improves, but the ease of manufacture decreases
Solution Approach 1:
The operating members are designed with standardized local features and interfaces that can be manufactured using common processes. Each operating member has specific engagement surfaces and connection points that are optimized for manufacturability while maintaining the functional requirements for achieving multiple speed ratios.
Data Source
AI summary
A powertrain of an automatic transmission includes a first planetary gear set having first, second, and third operating members, a second planetary gear set having fourth, fifth, and sixth operating members, and third planetary gear set having seventh, eighth, and ninth operating members, the fourth and seventh operating members being fixedly interconnected, the fifth and ninth operating members being fixedly interconnected, the third and eighth operating members being selectively interconnected, the second and seventh operating members being selectively interconnected, the second and sixth operating members being selectively interconnected, wherein a transmission case is fixedly connected to the first operating member and selectively connected to the seventh and eighth operating members, an input shaft is fixedly connected to the third operating member and selectively connected to the seventh operating member, and an output shaft is fixedly connected to the ninth operating member.