Compact Five-Speed Planetary Transmission Design
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Solution Overview
Problem
Conventional planetary gear transmissions require a large installation footprint due to the need for multiple gear sets to achieve a wide range of speed ratios, often limiting the number of reverse speed ratios available.
Innovation Solution
A compact transmission system utilizing five planetary gear sets, four brakes, and two clutches to achieve five forward and four reverse speed ratios, with selective actuation of brakes and clutches to optimize gear ratios and direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple planetary gear sets are used to achieve a wide range of speed ratios, then the number of forward and reverse speeds is improved, but the installation footprint increases
Solution Approach 1:
The patent merges multiple planetary gear sets into a single integrated planetary gear train where sun gears, ring gears, and carriers of different sets are interconnected. This allows multiple speed ratios to be achieved through selective engagement of clutches and brakes on shared components, reducing the overall footprint compared to separate gear sets.
Solution Approach 2:
The planetary gear train components serve multiple functions simultaneously. The same sun gears, ring gears, and carriers are used across different 'gear sets' to provide both forward and reverse speeds through different clutch and brake combinations, making each component multi-functional rather than dedicated to a single ratio.
2Area of stationary object
If the number of planetary gear sets is reduced to decrease installation footprint, then space requirements are improved, but the number of available reverse speed ratios deteriorates
Solution Approach 1:
The system uses dynamic engagement and disengagement of clutches and brakes during operation to switch between different reverse speed ratios. The selective actuation of these components allows the same physical gear train to dynamically provide multiple reverse speeds without requiring additional static gear sets.
Solution Approach 2:
The patent changes the operational parameters (which clutches and brakes are engaged) rather than changing the physical structure to achieve different reverse speeds. By varying the engagement state of the two clutches and four brakes, the system provides four different reverse speed ratios from a compact gear train configuration.
3Adaptability or versatility
If more clutches and brakes are added to provide multiple reverse speeds, then the number of reverse speed ratios is improved, but the device complexity increases
Solution Approach 1:
The patent uses a minimal number of clutches and brakes (two clutches and four brakes) to achieve the desired functionality. This is considered partial action in the sense that not all possible clutch and brake combinations are used, but rather a carefully selected subset that provides all necessary forward and reverse speeds with optimal complexity.
Data Source
AI summary
A compact five-speed transmission planetary gear train includes a first, second, third, fourth and fifth planetary gear sets between an input and an output as well as first, second, third and fourth brakes and first and second clutches. The first, second, third and fourth brakes and first and second clutches are selectively actuatable to provide five different forward speeds and a plurality of different reverse speeds between the input and the output.