Infinitely-Variable Transmission Regime Switching
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Solution Overview
Problem
Conventional transmissions for vehicles like backhoe loaders suffer from significant power losses and high fuel consumption due to the use of torque converters, especially at low speeds where the torque converter cannot be locked up, leading to inefficient drive characteristics.
Innovation Solution
A transmission system with a variator that provides a continuously variable ratio, allowing for low-speed, high-torque drive in both forward and reverse directions without the power losses associated with torque converters, using an epicyclic gearset and clutches to manage regimes and reduce power losses during regime changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a torque converter and multi-speed gearbox are used, then the transmission can provide drive in forward and reverse directions, but significant power losses occur at low speeds where the torque converter cannot be locked up
Solution Approach 1:
The transmission is divided into two distinct regimes: low-speed regime with geared neutral capability and high-speed regime with continuous variable transmission. This segmentation allows each regime to be optimized for its specific operating conditions, preventing power losses by avoiding torque converter operation at low speeds where locking is not possible.
Solution Approach 2:
The transmission dynamically switches between different operational modes (low-speed regime with epicyclic gearset and high-speed regime with CVT) based on operating conditions. The ability to engage geared neutral at low speeds and transition to CVT operation at high speeds creates a dynamic system that adapts to minimize power losses while maintaining drive capability.
2Force
If a torque converter is used, then the transmission can deliver high torque at low speeds, but fuel consumption increases due to inability to lock up the torque converter
Solution Approach 1:
The patent replaces the torque converter mechanical system with an epicyclic gearset for low-speed high-torque operation. This mechanical substitution eliminates the need for fluid coupling and allows direct mechanical power transmission through geared neutral, thereby eliminating the power losses and high fuel consumption associated with unlocked torque converters at low speeds.
Solution Approach 2:
The transmission changes operational parameters by switching between different gear ratios and transmission modes. At low speeds, the system engages geared neutral with specific epicyclic gearset configurations to deliver high torque efficiently. At high speeds, it transitions to CVT operation with different ratio parameters, optimizing fuel consumption across the entire operating range.
3Adaptability or versatility
If a variator ratio sweep is performed during regime transition, then the transmission can change from low-speed to high-speed regime, but drive cannot be passed without clutch slip and associated power loss and wear
Solution Approach 1:
The transmission performs preliminary actions by pre-positioning clutches and variator ratios before the actual regime transition. The direct engagement clutch is engaged in advance to establish a mechanical connection, and the variator ratio is pre-adjusted to match the target regime parameters, allowing transition without clutch slip or power loss.
Solution Approach 2:
The transmission maintains continuous useful action during regime transition by ensuring uninterrupted power flow through coordinated clutch engagement and variator ratio adjustment. The direct engagement clutch provides a continuous mechanical path for power transmission, while the variator smoothly adjusts ratios, eliminating gaps in useful action that would otherwise cause power loss and wear.
Data Source
AI summary
An infinitely-variable transmission system is disclosed. The system comprises an input shaft (10) and an output shaft (14). The transmission is operative to transmit rotational drive between the input shaft (10) and the output shaft (14). The transmission includes a variator (20) that can transmit drive at a continuously variable ratio between a minimum variator ratio and a maximum variator ratio. The transmission can operate a low-speed regime and in a high-speed regime. The transmission is operative in the low-speed regime, at a neutral low regime variator ratio, the transmission is in geared neutral, in which, the output of the transmission is stationary irrespective of the speed of the input of the transmission and at a maximum low regime variator ratio, the output of the transmission is driven from the input of the transmission at a maximum low-regime transmission ratio, In the high-speed regime, at a minimum high regime variator ratio, the output of the transmission is driven from the input of the transmission at a minimum high-regime ratio and at a maximum high regime variator ratio, the output of the transmission is driven from the input of the transmission at a maximum high-regime transmission ratio.