Dual-Clutch Transmission Range Shift Control Without Stopping
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Solution Overview
Problem
Dual-clutch transmissions (DCTs) have not been widely adopted in off-road vehicles due to high manufacturing costs and packaging issues, particularly in the limited engine compartment space, which hinders efficient packaging and performance.
Innovation Solution
A method for controlling a powertrain with a dual-clutch transmission that includes a first and second clutch, where the transmission can shift between high and low gear settings without stopping the vehicle, using a subtransmission with high and low transmission gears, and a controller to manage torque output and engine speed for efficient gear changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a dual-clutch transmission is used in an off-road vehicle, then gear shifting performance and efficiency are improved, but manufacturing costs and packaging complexity increase
Solution Approach 1:
The transmission system is divided into a main transmission with odd-numbered gears on a first shaft and even-numbered gears on a second shaft, with a separate subtransmission for high and low range selection. This segmentation allows independent optimization of each subsystem and enables parallel gear preselection, improving shifting efficiency while managing complexity through modular architecture
Solution Approach 2:
The system preselects gears on one shaft while the vehicle is being driven in a gear on the other shaft. This preliminary action allows the next gear to be ready before it is needed, enabling smooth, interruption-free shifts and improving productivity without requiring complex real-time control during the shift event
2Productivity
If a dual-clutch transmission is used in an off-road vehicle, then gear shifting performance is improved, but manufacturing costs increase
Solution Approach 1:
The subtransmission input shaft serves multiple functions: it receives torque from both the first and second shafts of the main transmission, and it drives the output shaft through either high or low range gears. This multi-functionality reduces the need for separate components and simplifies the overall manufacturing process while maintaining high shifting performance
Solution Approach 2:
The dual-clutch transmission uses two separate clutch assemblies (first clutch for odd gears, second clutch for even gears) that can be manufactured using similar processes and designs. This copying approach allows for standardized manufacturing techniques and component production, reducing overall manufacturing costs while achieving the desired performance
3Productivity
If a dual-clutch transmission is used in an off-road vehicle, then gear shifting efficiency is improved, but available space in the engine compartment is reduced
Solution Approach 1:
The subtransmission is integrated with the main transmission such that the subtransmission input shaft is driven by the main transmission shafts, and the high and low range gears are nested within the existing transmission housing. This nesting arrangement minimizes the overall footprint and allows the transmission system to fit within the limited engine compartment space while maintaining high shifting efficiency
Data Source
AI summary
A method for controlling a powertrain of a vehicle having a dual-clutch transmission (DCT) includes: operating the DCT while the vehicle is in motion with a high or low transmission gear drivingly engaged; receiving a shift request to engage an other one of the high and low transmission gears; reducing an engine torque output and first and second clutch torques; shifting a subtransmission to a neutral gear setting; selecting a first gear or a second gear to drive the subtransmission; shifting the main transmission to engage the selected first or second gear; after shifting the main transmission, shifting the subtransmission to the other one of the high and low transmission gears; and after shifting the subtransmission, controlling the engine torque output and the first and second clutch torques according to a driver request at an accelerator of the vehicle.