Star Worm Gear with Epicyclic Reduction for High-Speed Actuators
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Solution Overview
Problem
Conventional thrust reverser actuators face challenges with high rotational speeds exceeding the design limits of synchronization shafts, necessitating new technologies to manage these increased velocities effectively.
Innovation Solution
The implementation of a rotary-to-linear motion conversion device using a worm drive assembly and epicyclic gear assembly, which includes a worm shaft, worm wheel, sun gear, and planet gear, allowing for compact and lightweight gear reduction that synchronizes the actuation of thrust reverser systems, enabling operation with high-speed synchronization shafts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional back-driving worm gears are used, then the actuation system is reliable and simple, but the synchronization shafts cannot handle the high rotational speeds required by advanced thrust reverser technology
Solution Approach 1:
The gear system is segmented into multiple stages: a first worm gear stage for initial speed reduction, followed by a planetary gear stage for further reduction. This multi-stage segmentation allows the system to handle high input speeds by breaking down the speed reduction into manageable increments, preventing any single shaft from exceeding its design limits.
Solution Approach 2:
The planetary gear assembly acts as an intermediary between the high-speed worm shaft and the lower-speed output. The planetary gears mesh with both the worm wheel and a sun gear, providing an intermediate speed stage that protects the synchronization shafts from excessive rotational speeds while maintaining reliable actuation.
2Productivity
If high rotational speeds are implemented, then advanced thrust reverser technology can be achieved, but the synchronization shafts exceed their maximum design speed
Solution Approach 1:
The patent combines a worm gear mechanism and a planetary gear mechanism into a single integrated assembly. The planetary gears mesh with both the worm wheel and sun gear, creating a compact combined system that achieves high speed reduction ratios without requiring multiple separate gearboxes, thus managing complexity while enabling advanced technology.
Solution Approach 2:
The planetary gear set is nested within the worm gear assembly, with the planetary gears positioned inside the worm wheel structure. This nesting allows the complex multi-stage reduction system to be compact, fitting advanced high-speed actuation requirements into the existing actuator form factor without excessive complexity.
3Speed
If speed reduction is implemented to protect synchronization shafts, then rotational speed limits are maintained, but the gear assembly size and weight increase
Solution Approach 1:
The gear assembly utilizes composite construction methods, combining different materials optimized for specific functions: the worm shaft and gears use materials optimized for high-speed operation, while the planetary gear components use materials optimized for load-bearing and durability. This composite approach allows the assembly to be lighter while maintaining the speed reduction necessary to protect synchronization shafts.
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
This solution provides efficient rotary-to-linear motion conversion, enabling thrust reverser actuation systems to operate with high-speed synchronization shafts while maintaining a compact and lightweight design, reducing mechanical inefficiency and allowing for synchronous deployment or stowage of thrust reverser systems.
Implementation Method 1
a worm drive assembly having a worm shaft, and a worm wheel configured as a ring having a radially outer perimeter comprising a first collection of gear teeth extending radially outward from the radially outer perimeter and at least partly engaged with the worm shaft
Implementation Method 2
an epicyclic gear assembly having a sun gear and a planet gear engaged with the sun gear and the second collection of gear teeth
Implementation Method 3
a linear actuator assembly having a leadscrew engaged to the sun gear and responsive to revolution of the sun gear, and a nut engaged with the leadscrew and axially movable along the leadscrew in response to rotation of the leadscrew
Data Source
AI summary
The subject matter of this specification can be embodied in, among other things, an actuator that includes a worm drive assembly having a worm shaft, and a worm wheel configured as a ring having a radially outer perimeter comprising a first collection of gear teeth extending radially outward from the radially outer perimeter and at least partly engaged with the worm shaft, and a coaxial radially inner perimeter comprising a second collection of gear teeth extending radially inward from the inner perimeter, and an epicyclic gear assembly having a sun gear and a planet gear engaged with the sun gear and the second collection of gear teeth.