Pivotable Engine Mount Shackle for Load Sharing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing engine mount configurations for gas turbine engines face challenges in maintaining tight tolerance between the compressor case and shackle holes to prevent unequal load sharing and structural weight penalties, while also ensuring failsafe requirements are met against crack propagation and failure in engine case lugs.
Innovation Solution
The forward engine mount assembly features a pivotally connected link configuration with strategically positioned holes and a failsafe pin system that allows for load redistribution in case of failure, reducing the need for precise hole alignment and accommodating variations in hole sizes, thereby reducing structural weight and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the diameter of holes in the case and/or shackle is increased for a loose fit, then the manufacturing precision requirement is relaxed, but the structural weight increases and load sharing becomes unequal
Solution Approach 1:
The shackle is designed with a pivotable connection between the first and second links, allowing the connection geometry to dynamically adjust as pins engage with case holes. This dynamic adaptation enables the system to accommodate variations in hole positions and sizes without requiring tight manufacturing tolerances, while maintaining equal load distribution and avoiding weight penalties from oversized components.
Solution Approach 2:
The invention changes the geometric parameters of the shackle connection, transitioning from a fixed rigid connection to a pivotable connection with adjustable geometry. This parameter change allows the system to adapt to different hole configurations and maintain optimal load sharing without requiring precise hole alignment or increased component dimensions.
2Manufacturing precision
If the diameter of holes in the case and/or shackle is increased for a loose fit, then the manufacturing precision requirement is relaxed, but the load distribution becomes unequal
Solution Approach 1:
The pivotable connection allows the shackle to dynamically adjust its geometry as pins engage with case holes. This dynamic adjustment ensures that loads are equally distributed between the first and second links regardless of variations in hole positions or sizes, maintaining strength and load-sharing equality without requiring tight manufacturing tolerances.
3Device complexity
If a single plate configuration is used for the shackle, then the device complexity is reduced, but the reliability against crack propagation decreases
Solution Approach 1:
The shackle is segmented into two separate plates (first link and second link) that are pivotally connected. This segmentation prevents crack propagation from affecting the entire shackle structure, as a crack in one plate cannot propagate to the other plate. The segmentation maintains reliability while the pivotable connection keeps the overall device complexity manageable.
4Reliability
If additional failsafe requirements are implemented beyond the two-plate configuration, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The pivotable connection serves multiple functions: it provides the primary load-bearing connection, enables geometric adaptation to accommodate hole variations, and inherently provides failsafe functionality by allowing the shackle to maintain load paths even if one pin connection fails. This multi-functionality improves reliability without proportionally increasing device complexity.
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
This configuration ensures equal load sharing across engine case lugs, reduces structural weight, and enhances failsafe performance by providing an alternative load path, addressing the issues of unequal load distribution and weight penalties in existing designs.
Implementation Method 1
The pins are not tightly held within the holes due to the loose fit, one of the pins will be subjected to all of the engine's lateral loads before the other pin. The case and the shackle will then need to deform by a certain amount until the second pin banks against an edge of its hole and begins to share the load.
Implementation Method 2
the first and second links each include a third hole configured to receive a failsafe pin extending outwardly from the fore end of the mount beam
Data Source
AI summary
A forward engine mount assembly for a gas turbine engine includes a mount beam having a main body with a fore end and an aft end and a forward shackle assembly supported by the fore end of the mount beam. The forward shackle assembly comprises a first link configured to be connected to a first engine case structure and a second link configured to be connected to a second engine case structure. The first and second links are pivotally attached to each other.