Multi-speed transmission with planetary gear sets
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Solution Overview
Problem
Conventional automatic transmissions struggle to efficiently manage a wide range of vehicle speeds, as many engines operate optimally within a narrow speed range, requiring transmissions that can adapt power transmission ratios effectively across various speed conditions.
Innovation Solution
A family of transmission gearing arrangements utilizing four simple planetary gear sets and combinations of clutches and brakes to establish multiple speed ratios, including reverse and underdrive ratios, allowing for flexible speed relationships between input and output shafts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional automatic transmissions are used, then the transmission can operate over a wide range of vehicle speeds, but the engine cannot operate efficiently because it is limited to a narrow speed range
Solution Approach 1:
The transmission system employs multiple planetary gear sets with variable clutch engagement to dynamically adjust speed ratios. The system transitions between different gear configurations (first through fourth planetary gear sets) to provide nine forward speed ratios and one reverse speed ratio, enabling the transmission to adapt to various vehicle speeds while keeping the engine within its efficient operating range.
2Adaptability or versatility
If multiple speed ratios are implemented, then the transmission can adapt to various speed conditions, but the device complexity increases
Solution Approach 1:
The patent combines multiple planetary gear sets (first, second, third, and fourth planetary gear sets) into a single integrated transmission system. These gear sets share common components such as the input shaft, intermediate shaft, and output shaft, and are controlled by a unified clutch arrangement. This merging approach enables nine forward speed ratios and one reverse speed ratio to be achieved through coordinated engagement of clutches rather than requiring completely separate gear trains for each ratio.
Solution Approach 2:
The planetary gear sets are designed with multi-functionality where the same physical components serve multiple purposes. For example, the first planetary gear set can provide both a first speed ratio and a second speed ratio depending on clutch engagement, and the gear sets collectively provide underdrive ratios, direct drive ratio, and reverse ratio capabilities. This universal design reduces the number of dedicated components needed for each function.
Data Source
AI summary
A family of transmission gearing arrangements produces nine forward and one reverse speed ratio by selective engagement of various combinations of three clutches or brakes. Each transmission gearing arrangement includes a front shiftable gearing arrangement configured to establish a variety of speed ratios between an intermediate shaft and an input shaft. These speed ratios include a reverse speed ratio, a zero speed ratio, two underdrive ratios, and a direct ratio. Each transmission also includes a rear shiftable gearing arrangement configured to selectively establish particular speed relationships among the input shaft, the intermediate shaft, and an output shaft.