Foldable Wing Tip Actuation With Cascaded Rack-Pinion Torque Transfer
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Solution Overview
Problem
Existing actuation units for foldable wing tips in aircraft are not compact enough and face high torque requirements, making it difficult to employ similar units used for moving slats or flaps due to limited space and high mechanical demands.
Innovation Solution
A compact actuation unit comprising a motor, drive pinion, first rack, second rack, third rack, and transfer pinion, forming a cascaded kinematics system where the motor-driven drive pinion drives the third rack along a defined path, and the transfer pinion drives the second rack at twice the speed, enabling efficient and strong actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional rack and pinion actuation unit is used for foldable wing tips, then the actuation mechanism is simple and reliable, but the unit is too large and heavy for the limited space at wing tips
Solution Approach 1:
The actuation unit is divided into multiple independent rack components (first rack, second rack, third rack) that work together through a transfer pinion. This segmentation allows each rack to be optimized for specific functions while reducing the overall volume of the actuation unit compared to a single large rack and pinion system.
Solution Approach 2:
The transfer pinion is positioned to engage with both the third rack and the second rack simultaneously, creating a nested arrangement where the transfer pinion fits within the space between the two racks. This nesting approach maximizes space utilization and reduces the overall footprint of the actuation unit.
2Volume of moving object
If the actuation unit is made compact to fit limited wing tip space, then the volume is reduced, but the torque transmission capability deteriorates
Solution Approach 1:
The transfer pinion acts as an intermediary mechanism between the drive pinion and the second rack. It receives rotational motion from the third rack and converts it into motion that drives the second rack, enabling effective torque transmission through a compact arrangement of intermediate components rather than a single large direct-drive mechanism.
Solution Approach 2:
The actuation system utilizes multiple dimensions by arranging the three racks and transfer pinion in a three-dimensional configuration. The racks are positioned at different locations and orientations, with the transfer pinion bridging between them, thereby achieving compact power transmission through spatial arrangement rather than simply scaling up component sizes.
3Power
If a larger actuation unit is used to provide sufficient torque, then the torque transmission capability is improved, but the device complexity increases
Solution Approach 1:
The actuation unit is divided into multiple independent rack components (first rack, second rack, third rack) that work together through a transfer pinion. This segmentation allows each rack to be optimized for specific functions while reducing the overall volume of the actuation unit compared to a single large rack and pinion system.
Solution Approach 2:
The transfer pinion serves multiple functions simultaneously: it acts as a gear to receive motion from the third rack, serves as a mounting point for the second rack, and transmits power to the second rack. This multi-functionality reduces the need for separate dedicated components, thereby managing complexity while maintaining torque transmission capability.
4Volume of moving object
If the actuation unit is made compact for limited space, then the volume is reduced, but the actuation speed decreases
Solution Approach 1:
The transfer pinion acts as an intermediary mechanism between the drive pinion and the second rack. It receives rotational motion from the third rack and converts it into motion that drives the second rack, enabling effective torque transmission through a compact arrangement of intermediate components rather than a single large direct-drive mechanism.
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 provides a highly compact, fast, and efficient actuation unit that effectively operates the foldable wing tip portion, reducing the overall aircraft span during landing and parking by allowing for efficient torque transmission in a limited space.
Implementation Method 1
The drive pinion is driven rotationally by the motor, preferably via a gear unit. The third rack is drivingly engaged by the drive pinion for being driven along the first movement path
Implementation Method 2
The transfer pinion is mounted to the third rack rotatably about an axis of rotation extending perpendicular to the first movement path. The first rack engages the transfer pinion at a first side and the second rack engages the transfer pinion at an opposite second side of the circumference of the transfer pinion
Implementation Method 3
The third rack is configured to be mounted to the fixed wing movably along a defined first movement path, e.g. via a roller bearing
Data Source
AI summary
An actuation unit for actuating a foldable wing tip portion of a wing for an aircraft is disclosed including a motor configured to be mounted to a fixed wing for an aircraft, a drive pinion driven rotationally by the motor, a first rack configured to be mounted to the fixed wing, a second rack configured to be mounted to the foldable wing tip portion, a third rack configured to be mounted to the fixed wing movably along a defined first movement path and drivingly engaged by the drive pinion, and a transfer pinion mounted to the third rack rotatably about an axis of rotation extending perpendicular to the first movement path.