Planetary Gear Ring Support Friction Joint for Overload Slip
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Solution Overview
Problem
Planetary gearboxes in aircraft gas turbines face challenges in securely transmitting high torques while ensuring mechanical safety during overloads, as existing connections may fail unpredictably, leading to potential damage.
Innovation Solution
A frictional joint mechanism using bolt connections with a defined frictional force and a gap between the ring gear support and static component, allowing for controlled slipping during overloads, with a U-shaped covering device and flanges to maintain the connection and prevent bolt shear stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid mechanical connection is used to secure the planetary gearbox to the static component, then high torque transmission is achieved, but the connection may fail unpredictably during overload conditions
Solution Approach 1:
The connection transitions from a rigid static joint to a dynamic frictional joint that can slip during overload. The frictional joint allows controlled relative motion between the ring gear support and static component, enabling the connection to adapt its behavior based on load conditions while maintaining predictable failure characteristics.
Solution Approach 2:
The frictional joint changes the mechanical parameter from rigid constraint to friction-based constraint with defined slip characteristics. By controlling the friction coefficient and normal force through bolt preload, the system achieves both high torque transmission and predictable slip behavior during overload.
2Reliability
If a frictional joint with defined frictional force is used to connect the ring gear support to the static component, then controlled slipping during overload is achieved, but the connection may slip under normal operating conditions
Solution Approach 1:
The bolt connections are preloaded to generate sufficient normal force that creates a frictional force greater than the maximum operating torque but less than the overload torque. This preliminary action ensures the joint remains stable during normal operation while allowing controlled slip during overload conditions.
3Stability of the object's composition
If the ring gear support is rigidly fixed to the static component, then stable operation is achieved, but the device cannot safely dissipate overload energy
Solution Approach 1:
The frictional joint converts the harmful overload energy into useful frictional heating and controlled slip motion. During overload, the joint slips in a controlled manner, dissipating excess energy through friction while preventing catastrophic failure, thus transforming a potentially harmful effect into a protective 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 secure and reliable torque transmission system that can withstand high torques and safely disengage during overloads, minimizing damage and ensuring the frictional joint re-engages post-overload, maintaining operational integrity.
Implementation Method 1
the bolt connections are designed and arranged in such a way that there is a frictional joint with a defined frictional force between the ring gear support and the static component
Data Source
AI summary
The invention relates to a planetary gearbox having a ring gear support, in particular in a geared fan engine, characterized by a bolt connection for connecting the ring gear support to a static component, wherein the bolt connections are arranged on the circumference of the ring gear support in the axial direction of the planetary gearbox, and the bolt connections are designed and arranged in such a way that there is a frictional joint with a defined frictional force between the ring gear support and the static component and that a material separation, in particular a gap, is arranged between the ring gear support and the static component.