Planetary Carrier Stiffness Control for Gear Misalignment
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Solution Overview
Problem
Conventional planetary reduction gear apparatuses in aircrafts suffer from misalignment due to bending deformation of planetary shafts, leading to reduced lifespan and unbalanced contact between gears and bearings.
Innovation Solution
A planetary reduction gear apparatus with a planetary carrier having an annular base plate and back plate, where the base plate adjacent to one end of the planetary shaft has reduced stiffness through an axially extending through-hole, effectively suppressing bending deformation and misalignment by lowering the stiffness of the base plate relative to the back plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the planetary shaft is made with high stiffness to maintain alignment, then misalignment is reduced, but bending deformation under driving torque increases
Solution Approach 1:
The base plate is designed with non-uniform thickness, having a first thickness in the first region (adjacent to planetary shafts) and a second thickness in the second region (opposite side), creating different local stiffness characteristics. This allows the first region to be more compliant to reduce bending deformation while the second region maintains higher stiffness for structural support, thereby resolving the contradiction between alignment precision and bending resistance
2Strength
If the base plate stiffness is reduced to accommodate shaft bending, then misalignment occurs, but the shaft bending deformation is reduced
Solution Approach 1:
By creating regions of different stiffness in the base plate through variable thickness design, the invention allows each region to serve different functions: the first region with lower stiffness accommodates shaft bending without transmitting excessive stress, while the second region with higher stiffness maintains overall structural integrity and prevents excessive misalignment
3Strength
If the base plate material is reduced to lower stiffness, then bending deformation is reduced, but the weight increases
Solution Approach 1:
The base plate is segmented into different thickness regions (first and second regions) with distinct stiffness characteristics, allowing optimized material distribution that reduces weight while maintaining necessary structural performance in different areas
Solution Approach 2:
The variable thickness design ensures material is concentrated where needed (second region for structural support) and reduced where compliance is beneficial (first region for bending accommodation), achieving weight reduction without compromising overall strength
4Ease of manufacture
If the base plate structure is simplified to reduce manufacturing complexity, then production is easier, but the ability to control stiffness distribution is reduced
Solution Approach 1:
The variable thickness base plate can be manufactured using conventional forming processes, achieving different local stiffness characteristics through a single integrated component design, thus maintaining ease of manufacture while enabling precise stiffness control in different regions
Data Source
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AI summary
This apparatus (1) includes: a sun gear (5) having external teeth; planetary gears (7), each having external teeth and configured to be meshed with the sun gear (5); planetary shafts (13), each being a rotation shaft of the planetary gear (7); a ring gear (9) having internal teeth and configured to be meshed with the planetary gears (7); and a planetary carrier (11) including an annular base plate (17) and an annular back plate (19). The planetary carrier (11) supports the planetary shafts (13) between the angular base plate (17) and the annular back plate (19) and determines a relative position between planetary gears (7). The annular base plate (17) is integrally formed with one end of the planetary shaft (13) to support the one end. The annular back plate (19) supports the other end of the planetary shaft (13). At least one of the planetary shaft (13) and the planetary carrier (11) has lower stiffness in its part adjacent to the one end of the planetary shaft (13) than stiffness of its part adjacent to the other end thereof.