Agricultural Dual-Clutch Transmission Layout for Low-Loss Range Shifting
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Solution Overview
Problem
Current dual-clutch transmission architectures for agricultural vehicles suffer from high energy losses due to large wet clutches, significant inertia during gear shifting, and increased fuel consumption, necessitating improvements in efficiency, comfort, and compactness while reducing manufacturing time and weight.
Innovation Solution
The proposed dual-clutch transmission architecture features a staggered arrangement of clutches and gears, with an additional gearing module and a direct clutch swap mechanism in the range stage, allowing for efficient torque distribution and reduced inertia, enabling smoother shifting and increased compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If large wet clutches are used to enable range gear shifting, then gear shifting capability is improved, but energy loss increases
Solution Approach 1:
The transmission is divided into two independent clutch assemblies: a first clutch assembly for speed ratio changes and a second clutch assembly for range gear changes. This segmentation allows each clutch to be optimized for its specific function, enabling the use of smaller clutches overall while maintaining full shifting capability.
Solution Approach 2:
The patent introduces a dual-clutch architecture that operates in two distinct dimensional spaces: one clutch handles speed ratio transitions while the other manages range gear transitions. This dimensional separation eliminates the need for a single large clutch to handle all shifting operations simultaneously.
2Ease of operation
If traditional DCT architecture is used, then powershift capability is achieved, but fuel consumption increases during shifting
Solution Approach 1:
By segmenting the clutch functions into two separate assemblies, the patent reduces the inertia and energy requirements for each individual shifting operation. Each clutch can be smaller and lighter, reducing the energy penalty during engagement and disengagement cycles.
Solution Approach 2:
The independent second clutch assembly acts as an intermediary that pre-positions range gears without requiring torque transfer through the main clutch assembly. This mediator clutch enables smoother transitions and reduces the resistive torque that normally increases fuel consumption during shifts.
3Adaptability or versatility
If more gear ratios are provided, then transmission versatility is improved, but device complexity increases
Solution Approach 1:
The transmission system is segmented into two independent clutch assemblies, each managing a specific subset of gear changes. This segmentation allows for a higher total number of gear ratios to be achieved through coordinated operation of the two clutches without proportionally increasing the complexity of each individual clutch mechanism.
Solution Approach 2:
Each clutch assembly is designed with multi-functionality: the first clutch assembly can operate independently for speed ratios, the second clutch assembly can operate independently for range gears, and they can coordinate to provide the full spectrum of gear ratios. This universal design reduces overall system complexity.
4Ease of manufacture
If conventional clutch arrangement is used, then manufacturing is simplified, but transmission weight and axial extension increase
Solution Approach 1:
The patent arranges the two clutch assemblies in a staggered axial configuration rather than stacking them directly one after another. This dimensional arrangement reduces the overall axial extension of the transmission while maintaining manufacturing simplicity through standardized clutch component placement.
Solution Approach 2:
The second clutch assembly is positioned to overlap axially with the first clutch assembly, creating a nested arrangement where the clutches share common structural support elements. This nesting reduces the total weight and axial length without complicating the manufacturing process.
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).