Dual-Clutch Transmission Layout for Low-Loss Range Shifting
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Solution Overview
Problem
Existing dual clutch transmission (DCT) architectures for agricultural vehicles suffer from high energy dissipation and significant inertia during gear shifting, leading to inefficient fuel consumption and reduced comfort.
Innovation Solution
A dual clutch transmission architecture with a compact design that utilizes semi-synchronizers and a specific gear arrangement to minimize power losses and reduce clutch size, incorporating an input stage, gear ratio stage, and range gear ratio stage connected in series, with selective coupling via clutches and semi-synchronizers, controlled by an electronic control unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If big wet clutches are used to allow shift between range gears, then gear shifting capability is improved, but energy dissipation increases considerably
Solution Approach 1:
The transmission is divided into multiple stages (input stage, gear ratio stage, range gear ratio stage) with separate clutch assemblies for each stage. This segmentation allows smaller, specialized clutches to handle specific gear ranges instead of one large clutch handling all shifts, reducing overall energy dissipation while maintaining full shifting capability.
Solution Approach 2:
The system dynamically selects which clutch assembly to engage based on the required gear shift type (range gear shift vs. normal gear shift). The electronic control unit activates only the necessary clutch, optimizing energy efficiency by keeping clutches disengaged when not needed rather than maintaining constant engagement of large clutches.
2Adaptability or versatility
If traditional DCT architecture is used, then powershift capability is provided, but clutch size and inertia are considerable leading to high resistant torque
Solution Approach 1:
The clutch system is segmented into multiple smaller clutch assemblies (first clutch assembly for range gears, second clutch assembly for normal gears) instead of using single large clutch. This reduces the inertia of each individual clutch, thereby reducing resistant torque and energy consumption during shifting operations while preserving full powershift capability.
Solution Approach 2:
Different clutch assemblies are optimized for different functions: the first clutch assembly is designed specifically for range gear shifts while the second is designed for normal gear shifts. This localized optimization allows each clutch to be smaller and more efficient for its specific purpose, reducing overall energy consumption during shifting.
3Adaptability or versatility
If wet clutches are used extensively in semi-powershift or full-powershift transmissions, then powershift capability is improved, but power losses inside the transmission increase
Solution Approach 1:
The transmission uses segmented clutch assemblies distributed across different stages rather than extensive use of wet clutches throughout. This segmentation reduces the total number of wet clutches needed while maintaining powershift capability, thereby reducing power losses.
Solution Approach 2:
The system introduces an intermediate electronic control unit that mediates between the driver's gear selection and the physical clutch engagement. This allows for optimized control of clutch engagement timing and sequence, minimizing power losses during the transition periods when clutches are engaged and disengaged.
Data Source
AI summary
Architecture for a dual clutch transmission for an off road vehicle provided with an input stage, a gear ratio stage and a range gear ratio stage operatively connected in series one to the other with respect to an input shaft and an output shaft, the transmission comprises selection elements configured to selectively couple gears of the gear ratio stage to respective first and second shafts and selection means configured to selectively couple a range gear of the range gear stage to a support shaft and the rotatably free supported gears to an intermediate shaft.