Gearbox Mounting Assembly With Flex Coupling for Misalignment Control
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Solution Overview
Problem
The dynamic loading of gas turbine engines induces relative movements among gearbox components, leading to misalignments and increased stress, which can result in premature failure and wear of parts like bearings and seals, particularly in power gearboxes used to transfer torque from a turbine shaft to a fan shaft.
Innovation Solution
A mounting assembly for a gearbox assembly in a gas turbine engine, incorporating a flex coupling, flex mount, and fan frame to manage structural stiffness and damping, with configurations such as split sun gears and single piece ring gears to enhance load distribution and reduce misalignments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid mounting structure is used for the gearbox assembly, then the structural stability is improved, but the dynamic loading induces relative movements and misalignments among gearbox components
Solution Approach 1:
The mounting structure transitions from a purely rigid configuration to one with controlled flexibility through the flex mount and flex coupling. These components are designed with specific stiffness parameters that allow them to deform elastically under dynamic loading, accommodating relative movements between the gearbox and engine while maintaining proper gear alignment. The flex mount connects the gearbox to the engine with controlled compliance, and the flex coupling connects the input shaft to the turbine with similar properties.
Solution Approach 2:
The mounting structure is designed to be dynamically responsive rather than statically rigid. The flex mount and flex coupling allow the gearbox assembly to adapt its position and orientation in real-time under varying operational loads. This dynamic capability enables the system to absorb vibrations and maintain alignment despite changes in engine thrust and rotational forces.
2Reliability
If the gearbox components are tightly coupled to minimize relative movement, then the misalignment is reduced, but the stress concentration increases leading to premature failure
Solution Approach 1:
The flex mount and flex coupling serve as intermediary elements between the gearbox components and the engine structure. These intermediaries absorb and distribute dynamic loads, preventing stress concentration at critical interfaces. The flex mount intermediates between the gearbox case and engine mounting points, while the flex coupling intermediates between the input shaft and turbine, allowing each component to move independently within acceptable limits without transmitting excessive stress to connected parts.
Solution Approach 2:
The flex mount and flex coupling utilize flexible structural elements that can deform elastically under load. These flexible components are designed with appropriate material properties and geometric features that allow them to accommodate relative movements while distributing stresses uniformly across their structure, preventing stress concentration at any single point.
3Strength
If the mounting assembly uses multiple flexible components, then the load distribution is improved, but the device complexity increases
Solution Approach 1:
The mounting assembly is segmented into distinct functional components: the flex mount for connecting the gearbox to the engine, the flex coupling for connecting the input shaft to the turbine, and various mounting brackets and fasteners. This segmentation allows each component to be optimized for its specific function while simplifying the overall design and manufacturing process. Each segment can be independently analyzed, designed, and replaced if necessary.
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 improves the durability and extends the life of gearbox components by uniformly distributing torque loads and reducing eccentric loading, thereby minimizing gear degradation and failure.
Implementation Method 1
The dynamic loading of gas turbine engines induces relative movements among gearbox components... A mounting assembly for a gearbox assembly in a gas turbine engine, incorporating a flex coupling, flex mount, and fan frame to manage structural stiffness and damping
Implementation Method 2
A mounting assembly for a gearbox assembly in a gas turbine engine, incorporating a flex coupling, flex mount, and fan frame to manage structural stiffness and damping
Data Source
AI summary
A mounting assembly for a gearbox assembly of a gas turbine engine includes at least one mounting member configured to mount a gear of the gearbox assembly to a component of the gas turbine engine, the at least one mounting member characterized by a lateral impedance parameter, a bending impedance parameter, and a torsional impedance parameter. A gas turbine engine includes the mounting assembly. The at least one mounting member may be a flex mount, a fan frame, or a flex coupling. The gear includes a first gear that is a split sun gear including a forward sun gear and an aft sun gear separate from the forward sun gear. The forward sun gear and the aft sun gear are each rotationally coupled to a rotating shaft of the gas turbine engine.