Concentric DCT Gear Layout for More Shift Stages in Less Length
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Solution Overview
Problem
In vehicle powertrain design, there is a tradeoff between increasing shifting stages in transmissions and maintaining a short overall length, which affects fuel efficiency and vehicle mountability.
Innovation Solution
A dual-clutch transmission (DCT) configuration with concentric and parallel input and output shafts, drive and driven gears, and synchronizers to achieve multiple shifting stages while minimizing the transmission's length, including a sleeve synchronizer for connecting driven gears and a reverse idler shaft for reverse shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the shifting stages provided by the transmission are increased, then fuel efficiency is improved, but the whole length of the transmission becomes longer
Solution Approach 1:
The patent applies nesting by placing the second input shaft inside the first input shaft, and mounting drive gears for multiple shifting stages concentrically on the same shaft. This nested arrangement allows multiple gear sets to occupy the same radial space, enabling more shifting stages without increasing the transmission's axial length, thereby resolving the contradiction between fuel efficiency (requiring more stages) and length constraints.
Solution Approach 2:
The patent transitions from a conventional linear arrangement of gear sets to a concentric/circular arrangement where multiple drive gears are mounted on the same shaft at different radial positions. This dimensional reorganization allows multiple shifting stages to be packed into a compact axial footprint, increasing the number of available gear ratios without proportionally increasing the transmission length.
2Use of energy by moving object
If the shifting stages which is provided by the transmission increases, then the fuel efficiency is improved, but the vehicle mountability deteriorates
Solution Approach 1:
By nesting the second input shaft within the first input shaft and arranging drive gears concentrically, the patent reduces the overall transmission length to fit within the limited engine compartment width, thereby improving vehicle mountability while maintaining multiple shifting stages for fuel efficiency.
Solution Approach 2:
The concentric arrangement of multiple input shafts and drive gears transforms the transmission from a long axial structure to a compact radial structure, allowing it to accommodate more shifting stages within the lateral constraints of the vehicle's engine compartment, thus improving both fuel efficiency and mountability.
Data Source
AI summary
A dual-clutch transmission may include: a first input shaft and a second input shaft mounted concentrically to the first input shaft; a first clutch mounted to the first input shaft to selectively transmit power to the first input shaft; a second clutch mounted to the second input shaft to selectively transmit power to the second input shaft; a first output shaft and a second output shaft mounted in parallel with the first input shaft and the second input shaft; an input shaft connection device provided to switch a power transmitting and a blocking state between the first input shaft and the second input shaft by use of a selection output shaft; a plurality of drive gears mounted on the first input shaft and the second input shaft; and a plurality of driven gears mounted on the first output shaft and the second output shaft engaged with the plurality of drive gears to form each shifting stage.