Powershift Transmission Layout for Compact Full-Load Gear Shifting
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Solution Overview
Problem
Current powershift transmission assemblies for agricultural or earth-moving vehicles face challenges in achieving a high ratio between forward speeds in the highest and lowest gears while maintaining reduced speed jumps and a compact axial size, and they often fail to shift across all transmission ratios under load without interrupting torque transmission.
Innovation Solution
A transmission assembly with a limited axial size, featuring a high number of ratios and a ratio greater than 7 between the highest and lowest gears, achieved through a configuration with reduced friction clutches, coupling joints, and a design that allows all transmission ratios to be engaged under load, including a third transmission apparatus for additional selectable ratios and overall transmission ratio flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a high number of gears (more than 8-12 transmission ratios) is employed to achieve a high ratio between forward speeds in highest and lowest gears, then the speed ratio range is improved, but the axial size of the transmission assembly increases
Solution Approach 1:
The patent employs nested epicyclic gear sets where gears are arranged in concentric configurations. The first and second epicyclic gear sets share common shafts and planetary carriers, allowing multiple transmission ratios to be achieved within a compact axial footprint. This nesting approach enables 12+ gear ratios without proportionally increasing axial length.
Solution Approach 2:
The patent uses a universal selector device that can select between multiple gears (first gear, second gear, third gear) across different epicyclic gear sets. This multi-functional selector mechanism replaces what would traditionally require separate selection devices for each gear, reducing overall device complexity while maintaining the ability to provide 12+ transmission ratios.
2Reliability
If traditional friction clutches are used for gear selection under load, then torque transmission is maintained, but power losses increase
Solution Approach 1:
The patent replaces traditional friction clutch mechanisms with a synchronizer-based selection device. The synchronizer uses mechanical engagement of gear teeth with synchronization rings to achieve smooth gear changes under load. This mechanical substitution eliminates the sliding friction losses inherent in friction clutches while maintaining the ability to shift gears during torque transmission.
3Adaptability or versatility
If multiple friction clutches are used to achieve all transmission ratios under load, then gear selection capability is improved, but device complexity increases
Solution Approach 1:
The patent employs a universal selector device that can select between multiple gears (first gear, second gear, third gear) across different epicyclic gear sets. This multi-functional selector mechanism replaces what would traditionally require separate selection devices for each gear, reducing overall device complexity while maintaining the ability to provide 12+ transmission ratios.
Solution Approach 2:
The patent merges the first and second epicyclic gear sets into a unified transmission system where both gear sets share common shafts and planetary carriers. This consolidation allows the transmission assembly to achieve multiple transmission ratios through a single integrated structure rather than requiring separate, complex mechanisms for each gear set.
4Length of stationary object
If traditional transmission assemblies are designed with limited axial size, then compactness is improved, but the number of available transmission ratios is reduced
Solution Approach 1:
The patent employs nested epicyclic gear sets where gears are arranged in concentric configurations. The first and second epicyclic gear sets share common shafts and planetary carriers, allowing multiple transmission ratios to be achieved within a compact axial footprint. This nesting approach enables 12+ gear ratios without proportionally increasing axial length.
Solution Approach 2:
The patent utilizes radial arrangement of gears within the epicyclic gear sets, organizing transmission elements in the radial dimension rather than extending axially. This dimensional reorganization allows multiple gear ratios to be packed into a compact axial space by utilizing the radial space around the central shaft.
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 solution enables a compact, lightweight transmission assembly that achieves all available speed ratios under load with reduced power losses and noise, and eliminates the need for complex software interpretations, providing a seamless gear selection experience.
Implementation Method 1
a first friction clutch interposed between the first driving shaft and a first driven shaft
Data Source
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AI summary
A transmission assembly (10a, 10B) for motor vehicles is described which comprises an input shaft (15) and an output shaft (140) and is configured to transmit a rotation speed to the output shaft (140) and to modulate this rotation speed with respect to the rotation speed of the input shaft (15) making available a plurality of overall transmission ratios, which overall transmission ratios are all selectable under load. In particular, the shift from an overall transmission ratio to another one takes place without interrupting the transmission of the rotary motion from the input shaft to the output shaft, for each overall transmission ratio.