Brake Clutch Assembly for Propeller Windmilling Control
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Solution Overview
Problem
Gas turbine engine propulsion systems face unpredictability in propeller speed and bearing loading due to windmilling when the propeller is disengaged from the gearbox, leading to safety issues and premature wear in clutch assemblies.
Innovation Solution
A clutch assembly with a brake clutch mechanism that engages a stationary component to stop propeller rotation when disengaged, reducing windmilling and ensuring consistent bearing loading and lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the propeller is disengaged from the gearbox, then the clutch assembly can be maintained in a ready state for quick engagement, but the propeller speed becomes unpredictable due to windmilling
Solution Approach 1:
A brake clutch is introduced as an intermediary component between the second clutch element and the stationary component. When the first and second clutch elements are disengaged, the brake clutch engages with the second clutch element to prevent windmilling, thereby controlling propeller speed while maintaining clutch readiness for quick engagement
2Device complexity
If the propeller is disengaged from the gearbox, then the clutch assembly structure can be simplified, but bearing loading becomes inconsistent leading to premature wear
Solution Approach 1:
The brake clutch serves as a mediator that engages with the second clutch element when disengaged from the gearbox, providing consistent bearing loading through controlled friction. This prevents premature wear while maintaining the simplified clutch assembly structure
Solution Approach 2:
The brake clutch changes the friction parameter between the second clutch element and stationary component, transforming the uncontrolled windmilling state into a controlled state with consistent bearing loading, thereby extending bearing service life
3Reliability
If a brake clutch is added to stop propeller rotation, then propeller speed predictability is improved, but the clutch assembly complexity increases
Solution Approach 1:
The brake clutch is designed to perform multiple functions: it prevents windmilling when the clutch is disengaged, provides controlled friction to maintain bearing loading, and can be integrated into the existing clutch element structure. This multi-functionality justifies the added complexity by delivering comprehensive reliability improvements
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 effectively eliminates windmilling, enhances predictability of propeller speed, reduces safety risks, and prolongs clutch assembly lifespan by maintaining consistent bearing loading and minimizing lubrication when the brake is engaged.
Implementation Method 1
The brake clutch includes a brake clutch friction surface configured to engage the second friction surface of the second clutch element when the first clutch element and the second clutch element are disengaged. Engagement of the second clutch element and the brake clutch stops rotation of the propeller.
Implementation Method 2
The second clutch element includes a first friction surface configured to engage the first clutch element friction surface and a second friction surface opposite the first friction surface.
Data Source
AI summary
The disclosure describes a clutch assembly that includes a first clutch element coupled to an input shaft and including a first clutch element friction surface; a second clutch element coupled to an output shaft, and a brake clutch coupled to a stationary component. The second clutch element includes a first friction surface configured to engage the first clutch element friction surface and a second friction surface opposite the first friction surface. The second clutch element is configured to move relative to the first clutch element to engage and disengage the first friction surface and the first clutch element friction surface. The brake clutch includes a brake clutch friction surface configured to engage the second friction surface of the second clutch element when the first clutch element and the second clutch element are disengaged.