Helical Spline Clutch for Geared Turbofan Engine Torque Management
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Solution Overview
Problem
Gas turbine engines, particularly geared turbofan aircraft engines, face challenges in mitigating damage from failures such as shaft breakage, rotor-casing contact, or bearing seizure, which can lead to significant drag and require deliberate engagement or disengagement of engine parts, necessitating improved coupling and decoupling capabilities.
Innovation Solution
A mechanical clutch device with a helical spline connection and hydraulic means that automatically changes the position of connecting parts in response to torque, allowing for engagement and disengagement based on torque direction, enabling torque-free movement and balancing axial loads, and can be integrated with a propulsive fan for reduced aerodynamic drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical clutch device is used to couple/decouple connection parts in a gas turbo engine, then the reliability is improved by enabling deliberate disengagement to mitigate damage from failures, but the device complexity increases due to the need for automatic triggering means and torque transmission mechanisms
Solution Approach 1:
The clutch device automatically triggers position changes based on torque direction reversal without requiring external control systems. The helical spline connection and hydraulic means self-activate when torque reverses, enabling the system to protect itself from damage during failure events while maintaining simple integration into the existing engine architecture
Solution Approach 2:
A hydraulic means acts as an intermediary between the torque transmission path and the clutch actuation mechanism. This intermediary converts torque direction reversal into automated clutch engagement/disengagement, providing reliable failure mitigation while isolating the complexity of the automatic triggering mechanism from the main torque transmission path
2Object-affected harmful factors
If the propulsive fan is decoupled from the gearbox during failure events, then the harmful factors are reduced by eliminating drag from locked fans, but the productivity decreases due to loss of direct mechanical drive capability
Solution Approach 1:
The clutch device dynamically adjusts the coupling state between the propulsive fan and gearbox based on operating conditions. During normal operation, the fan is mechanically coupled for direct drive. During failure events with torque reversal, the system automatically decouples to eliminate drag, and can re-engage when conditions normalize, providing adaptive response to changing operational requirements
Solution Approach 2:
The system changes the mechanical coupling parameter (engaged/disengaged state) in response to torque direction changes. When torque reverses during a failure event, the clutch automatically transitions to disengaged state, eliminating the harmful drag effect. The asymmetric torque transmission characteristics enable this parameter change to occur automatically based on the physical state of the system
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 mechanical clutch device effectively manages torque transmission and axial loads, enabling safe disengagement of critical engine components, reducing drag, and allowing for windmilling operation or external power-driven propulsive fan operation, thereby enhancing engine reliability and efficiency.
Implementation Method 1
a hydraulic means for changing the position of the connecting parts depending on the torque effective on the connecting parts and/or the engine part
Implementation Method 2
a helical spline connection between the connection parts, an automatic clutch device and/or a hydraulic means for changing the position of the connecting parts depending on the torque effective on the connecting parts
Implementation Method 3
The propulsive fan (13) is frictionally coupled to a gearbox (14) of the geared aircraft turbofan engine (10)
Data Source
AI summary
A mechanical clutch device for coupling two connecting parts in a gas turbo engine, in particular a geared aircraft turbofan engine, with means to automatically trigger a position change of one of the connecting parts relative to the respective other connecting parts and/or relative to an engine part from the first position into a second position in dependence of a torque effective on the connecting parts and/or the engine part, in particular through the transmission via a shaft, in particular a non-nominal torque, more in particular a reversal in the direction of the torque. It also relates to a method for operating a mechanical clutch device.