Automatic Transmission Power Train With Single-Pinion Reverse Path
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Solution Overview
Problem
Conventional automatic transmissions with multiple planetary gear sets in a double-pinion structure suffer from inefficient gear efficiency, particularly in reverse shift positions, which affects fuel economy and acceleration performance.
Innovation Solution
Configuring all planetary gear sets in a single pinion structure and transmitting the reverse drive of a motor through the same power transmission path as the first shift position, allowing for improved gear efficiency and increased gear ratio in reverse shift positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the fourth planetary gear set is configured in a double-pinion structure, then the gear train can achieve multiple shift positions, but the gear efficiency deteriorates
Solution Approach 1:
The patent divides the complex double-pinion structure into separate single-pinion planetary gear sets. Each planetary gear set (PG1-PG4) is configured as an independent single-pinion unit, eliminating the inefficient double-pinion configuration while maintaining the ability to achieve multiple shift positions through different combinations of clutches and brakes acting on these segmented gear sets.
2Productivity
If more multi-stage shift positions are added to improve fuel economy and acceleration, then the power transmission efficiency improves, but the device complexity increases
Solution Approach 1:
The patent employs four single-pinion planetary gear sets that can be combined in various ways to achieve eight forward shift positions and one reverse shift position. Each planetary gear set serves multiple functions by being selectively engaged through different clutch and brake combinations, allowing the same basic structure to provide both forward and reverse operations across multiple stages without proportionally increasing complexity.
Data Source
AI summary
In a power train of an automatic transmission, a first carrier is integrally configured with a single pinion that is engaged with a first sun gear and a first ring gear, a second carrier is integrally configured with a single pinion that is engaged with a second sun gear and a second ring gear, a third carrier is integrally configured with a single pinion that is engaged with a third sun gear and a third ring gear, and a fourth carrier is integrally configured with a single pinion that is engaged with a fourth sun gear and a fourth ring gear, and in which a reverse shift position is implemented by transmitting a reverse drive of a motor through an input shaft to the same power transmission path as a first shift position.