Planetary Gear Stiffness Matching for Reduced Tooth Twist
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Solution Overview
Problem
Planetary gears in jet engines experience undesirable twisting and torsion due to applied torques, leading to reduced contact surfaces between tooth flanks and potential irreversible damage, which is exacerbated by the need for high structural component stiffness and weight to mitigate these issues, conflicting with design criteria for aircraft engines.
Innovation Solution
The structural component stiffnesses of the sun wheel, planetary carrier, and hollow wheel are adjusted to each other to minimize twisting, allowing for smaller tooth area deviations and larger contact surfaces, achieved through varying wall thicknesses and helical gearing with defined angle settings, reducing point loads and manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the structural component stiffness of the sun wheel, hollow wheel, planetary carrier and planetary wheel is increased to limit twistings, then the twisting and torsion during operation is reduced, but the structural component dimensions and weight increase
Solution Approach 1:
The patent applies local quality by varying the wall thickness of the planetary carrier in specific regions. The wall thickness is increased in areas subject to higher stresses (such as near the connection areas and tooth meshing zones) while maintaining thinner walls in less critical areas. This localized reinforcement provides the necessary stiffness to limit twistings and torsions during operation without uniformly increasing the weight of the entire planetary carrier, thus resolving the contradiction between structural stability and weight reduction.
2Reliability
If the structural component dimensions are increased to provide profile correction in the tooth meshing area, then the contact surface between teeth is improved, but the planetary gear installation space and weight increase
Solution Approach 1:
The patent applies parameter changes by optimizing the wall thickness distribution of the planetary carrier to control and adjust the twisting behavior of the component under load. By carefully selecting and varying the wall thickness parameters in different regions, the patent achieves appropriate profile correction in the tooth meshing area, ensuring sufficient contact surface quality between gears. This approach allows for reliable tooth contact without increasing the overall dimensions and volume of the planetary gear assembly.
Data Source
AI summary
A planetary gear with a sun wheel, a hollow wheel and a planetary carrier on which a planetary wheel is rotatably mounted. In the axial direction on a first side of the planetary carrier, the sun wheel and hollow wheel include connection areas for coupling the sun wheel and hollow wheel to rotatable or torque-proof areas of an engine. The planetary carrier has a connection area for attaching to rotatable or torque-proof areas of the engine on its opposite second side. The structural component stiffnesses of the sun wheel, planetary carrier, the hollow wheel and the planetary wheel are adjusted to each other such that, during operation they have twistings in the axial direction of the planetary gear that respectively qualitatively correspond to each other between the connection areas and side areas facing away from the connection areas due to the respectively applied torques.