Multi-speed Split Dual Clutch Transmission with Nested Planetary Gears
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Solution Overview
Problem
Conventional multi-speed dual clutch transmissions lack the range of torque and gear ratios necessary for commercial vehicles, leading to inefficient and undesirable transmission weights and sizes.
Innovation Solution
A transmission design featuring a split dual clutch assembly with two countershaft gearing arrangements, a planetary gear set, and a combination of clutches, brakes, and synchronizers to provide multiple forward and reverse gear ratios, including at least seventeen forward gear ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional clutches, brakes, and gear sets are added to achieve commercial vehicle torque ranges and gear ratios, then the transmission can provide the necessary torque and gear ratio range, but the transmission weight and size increase inefficiently
Solution Approach 1:
The patent employs nested planetary gear sets where smaller planetary gears are positioned within the annulus of larger planetary gears. This nesting arrangement allows multiple gear reduction stages to be compacted into a single transmission unit, achieving the required torque multiplication and gear ratio range without proportionally increasing transmission size or weight
Solution Approach 2:
The dual clutch assembly serves multiple functions simultaneously: it provides split clutch operation for smooth shifting, acts as a torque converter alternative for launch torque transmission, and enables multiple forward and reverse gear ratios through coordinated clutch engagement patterns. This multi-functionality reduces the need for separate components that would otherwise be required
2Adaptability or versatility
If additional clutches, brakes, and gear sets are added to achieve commercial vehicle torque ranges and gear ratios, then the transmission can provide the necessary torque and gear ratio range, but the transmission packaging efficiency deteriorates
Solution Approach 1:
The nested planetary gear configuration allows the transmission to achieve multiple gear ratios and torque ranges within a compact volume. By placing planetary gear sets concentrically within each other, the design maximizes the gear ratio range per unit volume, improving packaging efficiency for commercial vehicle applications
Solution Approach 2:
The patent combines the functions of multiple clutches, brakes, and gear sets into an integrated dual clutch assembly with nested planetary gears. This merging of components reduces the overall transmission volume by eliminating the need for separate component housings and mounting structures that would be required in conventional designs
3Device complexity
If a conventional multi-speed dual clutch transmission is used, then the transmission structure is simpler, but it lacks the range of torque and gear ratios necessary for commercial vehicles
Solution Approach 1:
The transmission is segmented into two independent countershafts (first and second countershafts) that can operate independently or in combination. Each countershaft has its own planetary gear set and clutch control, allowing the system to achieve a wide range of gear ratios and torque multiplication through selective engagement of different segments, thereby increasing adaptability while maintaining manageable complexity
Data Source
AI summary
A transmission is provided having an input member, an output member, a clutch assembly, two countershaft gearing arrangements, one planetary gear set, a plurality of interconnecting members, and a plurality of torque transmitting devices. Each of the countershaft gearing arrangements includes a plurality of co-planar gear sets. The torque transmitting devices include a combination of clutches, brakes, and synchronizers.