Multi-Mode CVT Drop Set Layout for Compact Split-Path Powertrains
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Solution Overview
Problem
Work vehicles require a powertrain system that can efficiently provide continuously variable power in multiple modes of operation, integrating both internal combustion engines and continuously variable power sources, while adhering to stringent packaging constraints and operational efficiency needs.
Innovation Solution
A multi-mode continuously variable transmission (CVT) system that includes a continuously variable power source, input, variator, and drop set arrangements, with a configuration of four primary shafts and few clutches, enabling selective gear reduction and power transmission modes, including CVP-only, split-path, and mechanical path modes, to meet various operational requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional multi-gear transmission system is used to provide multiple operation modes, then the versatility and adaptability of the powertrain system is improved, but the device complexity and packaging space requirements increase significantly
Solution Approach 1:
The patent implements a universal transmission architecture where a single continuously variable transmission system can operate in multiple modes (engine-only mode, CVP-only mode, and split-path mode) by using a shared planetary gear set and variable displacement mechanisms. This multi-functional design allows one transmission system to replace what would traditionally require multiple separate transmission systems, thereby reducing complexity while maintaining versatility.
Solution Approach 2:
The patent employs dynamic variability in the planetary gear set through variable displacement mechanisms that can continuously adjust gear ratios and power distribution. The ability to dynamically switch between different operating modes and continuously vary transmission ratios within each mode provides adaptability without requiring discrete fixed-gear mechanisms for each mode, thus reducing overall system complexity.
2Productivity
If a continuously variable power source is integrated with the engine, then the operational efficiency and power delivery flexibility is improved, but the packaging constraints and space requirements worsen
Solution Approach 1:
The patent merges the continuously variable power source (CVP) and the internal combustion engine into a unified powertrain system where both power sources share common transmission components. The planetary gear set serves both the engine and CVP, and the variable displacement mechanisms are shared across both power sources. This consolidation allows the system to achieve continuous variable power delivery and high operational efficiency while minimizing the total packaging space compared to having separate independent systems.
Solution Approach 2:
The patent implements a nested arrangement where the planetary gear set is positioned concentrically around the input shaft, and the variable displacement mechanisms are integrated within the existing transmission housing. The CVP and engine are arranged to share common mounting structures and transmission pathways, creating a compact nested configuration that maximizes space utilization and minimizes the overall volume of the powertrain assembly.
3Volume of moving object
If a compact transmission design is implemented to meet packaging constraints, then the volume and space requirements are reduced, but the availability of multiple gear ratios and transmission modes is limited
Solution Approach 1:
The patent uses dynamic variability mechanisms within the planetary gear set that allow continuous adjustment of gear ratios without requiring multiple discrete gear sets. The variable displacement mechanisms enable the system to continuously change transmission ratios and switch between operating modes within a compact single-stage planetary arrangement, providing diverse transmission modes and adaptability while maintaining a small footprint.
Solution Approach 2:
The patent designs a universal planetary gear set that can perform multiple functions: providing gear reduction in engine-only mode, enabling direct drive in CVP-only mode, and facilitating power combination in split-path mode. This single multi-functional gear set replaces what would traditionally require multiple separate gear trains for different modes, achieving transmission versatility within a compact volume.
Data Source
AI summary
A multi-mode CVT for a work vehicle powertrain has a continuously variable power source (CVP), an input arrangement with an input shaft receiving engine power, a variator arrangement with a variator shaft supporting a planetary set, a drop set arrangement with a drop set shaft, and an output arrangement with an output shaft supporting an output component. The input, variator, and drop set arrangements include clutch components with the clutch(es) of the drop set arrangement transmitting CVP power or combined CVP and engine power to the output arrangement to provide a selective gear reduction for transmission of an output power according to a plurality of transmission modes, including a CVP-only mode and a combined engine and CVP split-path mode.