Integrated Carrier Wave Generator for Compact Harmonic Drives
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Solution Overview
Problem
Existing actuation systems in aircrafts, such as those for moving control surfaces or rotating components in environmental control systems, require high gear ratios but often utilize complex geartrains with numerous moving parts.
Innovation Solution
A harmonic drive with a balanced epicyclic geartrain incorporating a carrier with an integrated wave generator, featuring a housing, epicyclic geartrain, and specific bearing configurations to achieve high gear ratios with reduced complexity and part count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If complex geartrains are used to achieve high gear ratios, then the gear ratio requirement is met, but the device complexity and number of moving parts increase
Solution Approach 1:
The patent combines the wave generator and carrier into a single integrated component. The wave generator is formed as an integral part of the carrier structure, eliminating the need for separate wave generator and carrier components. This merging reduces the number of moving parts while maintaining the high gear ratio functionality through the epicyclic geartrain mechanism.
Solution Approach 2:
The integrated carrier-wave generator component performs multiple functions simultaneously: it serves as the carrier that holds planet gears, generates the harmonic wave motion for the flexspline engagement, and provides structural support for the entire geartrain. This multi-functionality reduces overall device complexity while achieving the required gear ratio.
2Power
If complex geartrains with more moving parts are used, then high gear ratios are achieved, but the size of the actuation system increases
Solution Approach 1:
By merging the wave generator and carrier into one integrated component, the patent reduces the overall volume required for the actuation system. The elimination of separate components and their associated mounting structures, bearings, and fasteners results in a more compact design that maintains high gear ratio capability.
Solution Approach 2:
The epicyclic geartrain configuration allows nested arrangement of sun gear, planet gears, and ring gear in a compact cylindrical package. The integrated carrier-wave generator further enables compact nesting by eliminating internal clearances and mounting features that would be required for separate components.
3Power
If traditional geartrains are used, then high gear ratios are achieved, but the part count increases
Solution Approach 1:
The patent reduces part count by merging the wave generator and carrier into a single integrated component. This eliminates the need for separate wave generator, carrier, and associated mounting hardware, directly reducing the total number of parts in the assembly.
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 compact and efficient geartrain that reduces part count and size while maintaining high gear ratios, enabling smaller motors to drive heavy structures effectively.
Implementation Method 1
a flexspline that is deformable by the wave generator
Implementation Method 2
an epicyclic geartrain within the housing, wherein the epicyclic geartrain includes a sun gear, a plurality of planet gears, and a ring gear
Data Source
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AI summary
A harmonic drive having a housing (110) with an outer shell (120) defining an inner surface (110C); an epicyclic geartrain (150) within the housing; the geartrain includes a carrier (160); the carrier defines a center passage (170) and an outer surface (180), and wherein the center passage of the carrier receives an input shaft (190); the outer surface of the carrier defines a wave generator portion (200) that defines a wave generator (210); the harmonic drive has an output shaft (220) that has an output shaft forward portion (220A) and an output shaft aft portion (220B); the output shaft aft portion is within the housing and surrounds the carrier; the output shaft forward portion extends through a forward end of the housing; a flex spline (230) is defined by the output shaft aft portion; the flex spline is aligned with the wave generator; a circular spline (240) is defined along the inner surface of the housing; the circular spline is aligned with the flex spline.