Power Split Transmission Variator Gear Ratio Management
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Solution Overview
Problem
Existing power split transmissions for smaller working machines and tractors lack the ability to efficiently manage rotational speed variability and gear ratio spread, particularly in transitioning between driving ranges, leading to suboptimal performance and efficiency.
Innovation Solution
A power split transmission system comprising a continuous rotational speed variator, a summing gearset, and a multispeed transmission, with a shiftable transmission gear assembly using friction clutches to engage different gear ratios, allowing for adaptive variator adjustments and maintaining consistent torque load on the variator during driving range changes, while enabling modular design and electronic control for optimized performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a continuous rotational speed variator with a summing gearset is used, then rotational speed variability is improved, but the gear ratio spread is insufficient
Solution Approach 1:
The patent combines a continuous rotational speed variator (first part) with a multispeed transmission (second part) having multiple gear ratios into a single power split transmission system. The variator provides continuous speed adjustment while the multispeed transmission provides discrete gear ratio steps, merging the advantages of both systems to achieve both rotational speed variability and adequate gear ratio spread.
Solution Approach 2:
The transmission system is segmented into two functional parts: a first part containing the continuous variator for speed adjustment, and a second part containing the multispeed transmission for gear ratio selection. This segmentation allows each part to specialize in its function while working together to solve the overall problem of speed control and gear ratio spread.
2Ease of operation
If friction clutches are used for shifting gear ratios, then ease of operation is improved, but torque load consistency during shifts deteriorates
Solution Approach 1:
The control unit monitors the operating state of the transmission system and automatically controls the friction clutches for gear ratio changes. The system provides feedback on torque load conditions and adjusts the shifting process to maintain consistent torque load on the variator, ensuring reliable operation while maintaining ease of use through automated control.
Solution Approach 2:
The transmission system performs self-regulation during gear ratio changes by automatically adjusting the variator settings in response to clutch engagement. The control system monitors torque load and makes necessary adjustments without external intervention, maintaining torque consistency while the friction clutches handle the shifting operation automatically.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves improved rotational speed variability and gear ratio spread, enhancing vehicle performance by allowing the output shaft of the summing gearset to remain active across all driving ranges, even at maximum variator adjustment, and enabling seamless shifts between driving ranges with consistent torque load on the variator.
Implementation Method 1
the shiftable transmission gear assembly comprises friction clutches by means of which the gearshift can be carried out
Data Source
AI summary
A power split transmission which has a first part (2) and a second part (22). The first part (2) includes a variator (10), a summing gearset (6) and a shiftable transmission gear assembly (18). A standard transmission can be used as the multispeed transmission (23).