CVT-DCT Transmission Layout for Off-Road Shifting Without CVT Strain
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Solution Overview
Problem
Combining a continuously variable transmission (CVT) with a geared transmission in off-road vehicles presents challenges, including wear and tear on the CVT, complex shifting mechanisms, and reduced performance in off-road conditions, as well as utility purposes.
Innovation Solution
A vehicle configuration that integrates a CVT with a dual-clutch transmission (DCT), featuring a drive pulley, driven pulley, transmission belt, and dual clutches, allowing for seamless gear shifting and reduced strain on the CVT by enabling selective engagement of clutches for high, low, and reverse gears, improving shifting ease and off-road performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a CVT is combined with a geared transmission, then gear ratio shifting capability is improved, but wear and tear on the CVT increases
Solution Approach 1:
The transmission system is segmented into two independent parts: a CVT for continuous variable ratio adjustment and a DCT for discrete gear shifting. The DCT operates independently from the CVT, with its own clutch input member, shafts, and gear sets, allowing each subsystem to function optimally without interfering with the other, thus preventing wear on the CVT while maintaining gear shifting capability
Solution Approach 2:
The DCT acts as an intermediary between the engine and the final drive, providing discrete gear ratios through its own transmission path. This intermediary system allows the CVT to operate in its optimal range without being strained by gear shifting requirements, as the DCT handles the discrete ratio changes independently
2Adaptability or versatility
If a CVT is combined with a geared transmission, then gear ratio options are improved, but complexity of the transmission system increases
Solution Approach 1:
The transmission system is divided into modular segments: the CVT section with drive and driven pulleys for continuous adjustment, and the DCT section with clutch input members, shafts, and gear sets for discrete ratios. This segmentation allows each module to be optimized independently and simplifies maintenance and control compared to a fully integrated complex system
Solution Approach 2:
The DCT is designed with multi-functionality, serving both as a gear shifter and as a protective element for the CVT. The clutch input member can selectively engage different gear sets based on driving conditions, providing universal adaptability across various operating scenarios without requiring additional complex mechanisms
3Adaptability or versatility
If a geared transmission is added to the CVT, then off-road performance is improved, but strain on the CVT increases
Solution Approach 1:
The transmission system segments the torque path so that the DCT handles high-torque off-road conditions through its robust gear sets and clutch mechanism, while the CVT operates in a protected manner with reduced strain. The DCT's independent clutch input member allows torque to be routed through the gear system rather than placing excessive stress on the CVT belt and pulleys
Solution Approach 2:
The DCT is positioned beforehand in the torque transmission path to cushion and protect the CVT from excessive strain during off-road operations. The clutch input member and gear sets absorb and manage high-torque loads before they reach the CVT, preventing damage and extending the life of the transmission belt
Data Source
AI summary
A vehicle includes a continuously variable transmission (CVT) and a dual-clutch transmission (DCT) operatively connected to the CVT, the DCT includes a clutch input member operatively connected to a driven pulley of the CVT to be driven thereby; a first clutch; a second clutch; a first shaft operatively connected to the first clutch, the first clutch being selectively actuated to couple the first shaft to the clutch input member; a second shaft operatively connected to the second clutch, the second clutch being selectively actuated to couple the second shaft to the clutch input member; at least one first driving member mounted to the first shaft; at least one second driving member mounted to the second shaft; and an output shaft operatively connecting the at least one first driving member and the at least one second driving member to at least one ground-engaging member of the vehicle.