Mid-Turbine Frame Segmented Spoke Assembly
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Solution Overview
Problem
The existing mid-turbine frames in gas turbine engines face challenges in efficiently supporting bearing loads and routing airflow between high and low pressure turbine stages while maintaining structural integrity and manufacturing tolerance insensitivity.
Innovation Solution
A mid-turbine frame design featuring an inner frame case with a bolt opening and radially extending inlet passages, secured by a central bolt with external threads engaging internal threads on spokes, and featuring airflow passages and tabs for enhanced structural support and airflow management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional mid-turbine frame designs are used, then structural integrity is maintained, but manufacturing tolerance sensitivity increases and assembly complexity increases
Solution Approach 1:
The mid-turbine frame is segmented into an inner frame case, outer frame case, and multiple spokes. The inner frame case includes a bolt opening that receives a bolt for securing spokes, while the outer frame case is connected to the inner frame case via the spokes. This segmentation allows each component to be manufactured separately with standard tolerances and assembled together, reducing sensitivity to cumulative manufacturing tolerances while maintaining overall structural integrity.
Solution Approach 2:
The bolt acting as a central fastening element serves as an intermediary component that mediates the connection between the inner frame case and the spokes. The bolt includes a head that engages with the inner frame case and threads that engage with the spoke, providing a standardized interface that simplifies manufacturing and assembly while ensuring reliable load transfer.
2Reliability
If traditional mid-turbine frame designs are used, then structural integrity is maintained, but assembly complexity increases
Solution Approach 1:
The frame is divided into modular segments (inner frame case, outer frame case, spokes) that can be manufactured and inspected independently, then assembled in a straightforward sequence using standard fastening operations.
Solution Approach 2:
The standardized bolt with head and threads acts as an intermediary fastening element that simplifies the assembly process by providing a ready-made, standardized connection interface between the inner frame case and spokes, eliminating the need for complex custom fastening mechanisms.
3Force
If bearing loads are transferred through the mid-turbine frame, then structural support is provided, but stress concentration increases at connection points
Solution Approach 1:
The load transfer path is segmented through multiple discrete connection points (bolts securing multiple spokes) rather than concentrating forces at a single location. The inner frame case includes a bolt opening that receives a bolt for securing at least one spoke, distributing bearing loads across multiple standardized fastening points.
Data Source
AI summary
A method of assembling a mid-turbine frame includes engaging at least two tabs in a radially inner end of at least one spoke in a groove in an inner frame case. The at least one spoke is secured to the inner frame case with a central bolt extending through the inner frame case into the at least one spoke.