Agricultural Dual-Clutch Transmission With Offset Clutches
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Solution Overview
Problem
Current dual-clutch transmission architectures for agricultural vehicles suffer from high energy losses and inefficiency due to large wet clutches, leading to increased fuel consumption and discomfort during gear shifting, while also being cumbersome and costly to manufacture.
Innovation Solution
A dual-clutch transmission architecture with axially offset and staggered even and odd clutches, combined with a gear ratio stage and range gear stage, reduces energy losses by splitting torque through multiple paths and utilizing fewer wet clutches, allowing for smoother shifting and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If large wet clutches are used to enable range gear shifting in dual-clutch transmission, then gear shifting capability is improved, but energy losses increase and fuel consumption rises
Solution Approach 1:
The transmission is divided into two independent clutch assemblies (first and second clutch assemblies), each responsible for specific clutch sets. This segmentation allows each clutch to be optimized for its specific function, reducing the size and energy loss of individual clutches while maintaining overall shifting capability.
Solution Approach 2:
The patent introduces an axial offset arrangement where clutch sets are positioned at different axial locations. The first clutch assembly handles clutches at one axial position while the second clutch assembly handles clutches at another axial position, enabling range gear shifting without requiring a single large clutch.
2Ease of operation
If traditional dual-clutch architecture is used with big wet clutches for range gear shifting, then shifting functionality is achieved, but transmission weight and encumbrance increase
Solution Approach 1:
By dividing the clutch control function into two separate clutch assemblies positioned at different axial locations, each assembly can use smaller, lighter clutches optimized for specific shifting tasks, reducing overall transmission weight compared to a single large clutch system.
Solution Approach 2:
Each clutch assembly is designed to handle only the specific clutch sets required for its function, rather than using oversized clutches that would be needed to handle all clutch sets. This partial action approach reduces the size and weight of each clutch while maintaining complete shifting functionality through the combined action of both assemblies.
3Adaptability or versatility
If conventional DCT architecture with multiple wet clutches is implemented, then high number of speed ratios are achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The transmission is segmented into two clutch assemblies with distinct functional responsibilities. The first clutch assembly manages specific clutch sets for certain gear transitions, while the second clutch assembly manages different clutch sets for other transitions. This segmentation simplifies the control logic and manufacturing process compared to managing all clutches through a single assembly.
Solution Approach 2:
The patent introduces a synchronizer as an intermediary mechanism that works in conjunction with the clutch assemblies. The synchronizer facilitates smooth gear transitions by matching speeds before engagement, reducing the complexity of clutch control and enabling high-speed ratio transmissions with simpler manufacturing requirements.
4Force
If resistant torque is high during gear ratio or range gear ratio shifting, then shifting force is sufficient, but fuel consumption becomes significant
Solution Approach 1:
By dividing the shifting operation into two independent clutch assemblies, each handling specific clutch sets, the resistant torque during shifting is distributed across smaller, more efficient clutches. This reduces the peak torque requirements and associated energy losses compared to using a single large clutch for all shifting operations.
Solution Approach 2:
The dual-clutch architecture allows one clutch assembly to be pre-engaged and ready while the other disengages, enabling smoother transitions with lower peak resistant torque. This preliminary preparation of alternative torque paths reduces the energy required for shifting operations.
Data Source
Figure 1
Figure 1A
Figure 2
AI summary
Architecture for a dual clutch transmission (1) for an off road vehicle provided with an input stage (A), a gear ratio stage (B) and a range gear ratio stage (C) operatively connected in series one to the other with respect to an input shaft (2) and an output shaft (3), the transmission (1) comprises selection elements (17) configured to selectively couple gears (14, 15) of gear ratio stage (B) to respective first and second shafts (11, 12) and a gearing module (30) defining intermediate speed ratios with respect to the speed ratios of the rage gear ratio stage (C).