Curvilinear Turbomachinery Coupling to Prevent Rotor Overspeed
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In aircraft gas turbine engines, the disengagement of splined teeth in curvic couplings due to tie rod failure can lead to overspeed situations, which are difficult to quantify and pose serious safety risks due to uncontrolled sequence between tie-rod failure and blockage of rotating elements.
Innovation Solution
A toothed coupling mechanism with protrusions located off-axis on one of the splined teeth to prevent complete disengagement, causing tilting and misalignment, resulting in friction with the stator and braking of the rotor when uncoupling occurs, thereby controlling the consequences of tie rod breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a curvic coupling with splined teeth is used to transmit torque between rotating elements, then torque transmission capability is improved, but the risk of complete disengagement and overspeed increases upon tie rod failure
Solution Approach 1:
A protrusion is added to one of the splined teeth that will contact a corresponding tooth on the opposing coupling half before complete disengagement occurs. This preliminary contact action prevents the coupling halves from fully separating, thereby avoiding overspeed conditions while maintaining the torque transmission capability of the splined teeth during normal operation.
2Ease of operation
If the coupling mechanism allows free movement of coupling halves, then ease of assembly is improved, but uncontrolled sequence of events during uncoupling occurs
Solution Approach 1:
The protrusion on the splined tooth provides a preliminary restraining force that opposes complete disengagement. This creates a controlled sequence where the protrusion contacts the opposing tooth first, preventing chaotic movement and making the uncoupling sequence predictable and detectable.
3Reliability
If multiple protrusions are added to prevent disengagement, then reliability is improved, but device complexity increases
Solution Approach 1:
Instead of adding multiple protrusions throughout the coupling mechanism, a single protrusion is strategically placed on one of the splined teeth. This localized modification provides the necessary disengagement prevention while maintaining simplicity in the overall device structure.
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 mechanism ensures that the rotor remains in contact with static parts, preventing overspeed situations by generating friction that slows down the high-pressure turbine rotor, effectively managing the sequence of events during uncoupling and maintaining engagement until the rotor is blocked.
Implementation Method 1
the protrusion on the distal end will create a tilting zone of one of the coupling halves, thus of one of the rotating elements, with respect to the other, with a consequent misalignment of this element. This should cause friction against parts of the stator of the turbomachine, leading to heating as a result of the contact, which will lead to braking of the rotor.
Data Source
AI summary
A toothed coupling mechanism for an assembly of rotating elements of an aircraft gas turbine engine includes a pair of coupling halves having an axial toothed coupling interface therebetween. Each coupling half has a plurality of splined teeth inter-engaged about an axis for transmitting torque therebetween. A protrusion is located on one of the splined teeth of one of the coupling halves. A splined tooth of the other coupling half comes into contact with the protrusion in a situation of uncoupling of said coupling halves.