Multi-Shaft Gearbox Wet Clutch Layout for Seamless Short-Shifting
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Solution Overview
Problem
Dual-clutch transmission (DCT) technologies in high-performance cars are limited by their inability to perform seamless short-shifting, which restricts the gear shifting flexibility and efficiency, unlike conventional passenger cars with wide-ratio transmissions.
Innovation Solution
A gearbox configuration with rigid shafts and multiple wet clutches allows for seamless torque transfer and short-shifting by engaging and disengaging specific gear assemblies, eliminating the need for synchronizer rings and reducing weight by integrating clutch functions within gear assemblies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a close-ratio DCT is used in high-performance cars, then the engine can remain in the narrow operating interval for maximum power, but seamless short-shifting is not possible
Solution Approach 1:
The transmission is divided into two independent clutch systems (first clutch system with first and second gear assemblies, second clutch system with third and fourth gear assemblies), each capable of independent engagement and disengagement. This segmentation allows selective gear changes including short-shifting by disengaging specific clutches in sequences that were previously impossible in conventional DCTs.
Solution Approach 2:
The system dynamically adjusts which clutches are engaged based on driving conditions and desired gear changes. The control system can selectively engage/disengage clutches in various sequences to achieve different gear transitions including short-shifting, providing dynamic adaptability while maintaining the close-ratio configuration for acceleration performance.
2Productivity
If frequent gear shifting is performed in close-ratio transmissions, then the engine remains in the maximum power interval, but wear on gear assemblies increases
Solution Approach 1:
The system performs preliminary engagement of the target gear assembly's clutch before disengaging the current gear assembly's clutch during gear transitions. This preliminary action ensures that the target gear is already prepared and engaged, reducing the mechanical shock and wear that would occur from sudden gear changes, thereby extending gearbox lifespan while maintaining frequent shifting capability.
3Ease of operation
If seamless torque transfer is achieved in DCT, then gear shifting is smooth, but short-shifting is not possible
Solution Approach 1:
The system uses the second shaft as an intermediary torque transfer path. When performing short-shifting, torque can be transferred through the second shaft and the appropriate gear assemblies, allowing seamless torque delivery while achieving gear ratios that would otherwise require skipping gears. The multiple clutch systems act as intermediaries that enable flexible gear transitions without interrupting torque flow.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables smooth gear shifting with seamless torque transfer and reduced wear, allowing high-performance cars to operate with less frequent gear changes, similar to conventional passenger cars, while minimizing power loss and extending gearbox lifespan.
Implementation Method 1
Each gear assembly (20, 30) has a wet-clutch (26, 36) centered on one of the shafts (14, 16, 18)
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A gearbox (10) is provided having: a gearbox case (12), a first shaft (14) for receiving torque, a second shaft (16) for transferring torque inside the gearbox case (12), and a third shaft (18) for delivering torque. The gearbox further has three or more first gear assemblies (20) located inside the gearbox case (12), wherein each first gear assembly (20) comprises a first gear wheel (22) centered on the first shaft (14), a second gear wheel (24) centered on the second shaft (16), and a wet clutch (26) configured for operationally connecting the first shaft (14) and the second shaft (16). The gearbox also has three or more second gear assemblies (30) located inside the gearbox case (12), wherein each second gear assembly (30) comprises a third gearwheel (32) centered on the second shaft (16), a fourth gear wheel (34) centered on the third shaft (18), and a wet clutch (36) configured for operationally connecting the second shaft (16) and the third shaft (18).