Nested Gear Train Double Clutch Transmission Design
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Solution Overview
Problem
Current double clutch transmissions (DCTs) face challenges in increasing the number of speed stages without increasing the overall length and weight, which affects fuel efficiency and manufacturing costs.
Innovation Solution
A DCT design utilizing four or five gear trains and four synchro devices, with input shafts arranged as dual hollow pipes on a coaxial line, allows for eight forward speeds and one reverse speed by strategically positioning and operating clutches and synchro devices to minimize length and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If gear trains are added to increase the number of speed stages, then the number of speed stages increases, but the whole length and weight of the transmission increase
Solution Approach 1:
The patent employs nested gear trains where gears are arranged concentrically and share common axes. Multiple gear trains are nested within each other, allowing eight forward speeds and one reverse speed to be achieved without proportionally increasing the transmission's overall length. The gear trains are positioned at different radial distances from the central axis, enabling compact packaging of multiple speed stages.
Solution Approach 2:
The patent transitions from a linear arrangement of gear trains to a multi-dimensional configuration where gear trains are distributed in both radial and axial directions. By utilizing the radial dimension for nesting gears at different distances from the axis and the axial dimension for positioning input and output shafts, the design achieves multiple speed stages without linearly increasing the transmission's length.
2Adaptability or versatility
If gear trains are added to increase the number of speed stages, then the number of speed stages increases, but the weight of the transmission increases
Solution Approach 1:
The nested gear train configuration allows multiple gear sets to share common mounting locations and support structures. By nesting gears concentrically, the patent reduces the total amount of structural material needed compared to separate, distributed gear trains, thereby increasing speed stages without proportionally increasing transmission weight.
Solution Approach 2:
The patent designs gear trains that can serve multiple functions: the same gear train structure is used for both forward speed transmission and reverse speed generation. The synchro devices and clutch mechanisms are configured to control multiple gear trains simultaneously, reducing the need for separate control systems for each speed stage and thereby reducing overall weight.
3Device complexity
If the number of synchro devices is reduced, then the structure is simplified, but the ability to control multiple gear trains is compromised
Solution Approach 1:
Each synchro device in the patent is designed to control multiple gear trains simultaneously. The synchro devices are positioned to engage with several gear trains at once, allowing a single synchro mechanism to perform the function of what would otherwise require multiple separate synchro devices. This multi-functional design simplifies the overall structure while maintaining full control capability over all gear trains.
Solution Approach 2:
The patent merges the control functions of multiple synchro devices into fewer, more versatile synchro mechanisms. By combining control capabilities, the design reduces the total number of synchro devices needed while ensuring that each remaining device can independently control the necessary gear trains for smooth shifting between all speed stages.
Data Source
AI summary
A double clutch transmission (DCT) provides eight forward speeds and one reverse speed while minimizing the number of gear trains used for changing speed and the whole length thereof. In particular, the DCT has a simple structure using four or five gear trains and four synchro devices and is capable of providing eight forward speeds and one reverse speed while reducing the entire weight thereof. In a conventional DCT, when a gear train is added to increase the number of speed stages, the whole length thereof is increased. The provided DCT can minimize the whole length and the weight thereof, thereby reducing the manufacturing cost, the number of parts, and the fuel efficiency.