Dual-Clutch Transmission Layout for Skip Shifting and Shaft Alignment
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Solution Overview
Problem
Existing transmission designs face challenges in providing a sufficient number of gear ratios for skip shifting at lower speeds while maintaining an adequate range of operation at higher speeds, leading to increased input shaft length and eccentricity issues.
Innovation Solution
The proposed transmission architecture features a 3×3×2 configuration with a dual clutch transmission (DCT) or automated manual transmission (AMT) design, incorporating a spline joint to minimize radial displacement and misalignment, allowing for 18 gear combinations with smaller ratio steps and improved radial alignment, and includes a dual countershaft arrangement for efficient gear shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of gear ratios is increased to facilitate skip shifting in lower gears, then fuel efficiency and shifting performance are improved, but the input shaft length increases which compounds eccentricity problems
Solution Approach 1:
The transmission is divided into two separate shafts (input shaft and countershaft) with gears mounted on the countershaft. This segmentation allows multiple gear ratios to be achieved through gear combinations rather than extending the input shaft, thereby increasing gear ratios without proportionally increasing input shaft length and eccentricity.
Solution Approach 2:
Instead of achieving multiple gear ratios by extending the input shaft in one dimension, the patent uses a dual-shaft configuration where gears are mounted on a separate countershaft. This dimensional reorganization allows for more gear ratio options without linearly increasing the input shaft length, thus maintaining acceptable eccentricity levels.
2Adaptability or versatility
If more gear ratios are added for skip shifting capability, then the range of operation at higher speeds is improved, but the transmission layout complexity increases
Solution Approach 1:
The transmission system is segmented into two functional shafts: the input shaft for power input and the countershaft for gear ratio multiplication. This segmentation enables a compact layout that achieves multiple gear ratios through gear combinations on the countershaft, improving adaptability without proportionally increasing layout complexity.
Solution Approach 2:
The countershaft serves multiple functions: it carries multiple gears for different ratios, transmits power from the input shaft, and enables both skip shifting and high-speed operation. This multi-functionality allows a single component to provide versatile operation across different speed ranges without requiring separate dedicated components for each function.
3Ease of operation
If a dual clutch transmission is used to enable power shifting, then shifting smoothness is improved, but the device complexity increases
Solution Approach 1:
The dual clutch system prepares both gear sets in advance - one clutch engages the current gear while the other clutch is already positioned to engage the next gear. This preliminary preparation allows for smooth power shifting without torque interruption, improving shifting smoothness while the modular clutch design helps manage the added complexity.
Solution Approach 2:
The dual clutch arrangement acts as an intermediary mechanism that decouples the torque transmission from the gear shifting action. By using two clutches that can operate independently, the system mediates between the engine torque and the gear changes, enabling smooth shifts while the clutch control system manages the complexity of coordinating both clutches.
Data Source
AI summary
A transmission includes a main shaft having two or more main shaft clutches that couple gears to at least one countershaft, and an automated manual transmission coupled to the main shaft via the at least one countershaft. The automated manual transmission includes a front input shaft coupled directly to a main clutch and having a first clutch coupleable to the at least one countershaft, and a rear input shaft coupled to the front input shaft and having a second clutch coupleable to the at least one countershaft. The automated manual transmission is operable to selectively engage the first clutch and the second clutch.