Pinned Seal Assembly for Gas Turbine Blind Installation
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Solution Overview
Problem
The assembly of seals in gas turbine engines is complicated due to their difficult-to-access locations, requiring blind assembly and tight tolerances, which increases time and cost, especially when multiple seals are involved.
Innovation Solution
The use of a pin and hole configuration with varying cross-sectional gap areas, where a second pin and secondary pin hole have a larger gap area than a first pin and main pin hole, along with a bolt hole positioned between them, simplifies the assembly process by allowing for a blind assembly without the need for heating, thus reducing complexity and time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a snap-fit seal is used to create an air-tight interface, then sealing reliability is improved, but assembly complexity and time increase due to blind assembly requirements and tight tolerances
Solution Approach 1:
The seal assembly is divided into multiple components: a seal body with an air-tight interface, a separate locating pin with a locating feature, and a retaining feature. This segmentation allows the locating function to be separated from the sealing function, simplifying the overall assembly process while maintaining sealing reliability.
Solution Approach 2:
The locating pin is pre-installed in the housing before the seal is assembled. The locating feature on the pin protrudes into the seal's locating bore, establishing the correct position and orientation of the seal in advance. This preliminary action eliminates the need for complex blind alignment during final assembly.
2Reliability
If tight tolerances are applied to the snap-fit interface, then sealing reliability is improved, but manufacturing cost and assembly time increase
Solution Approach 1:
The locating function is segmented into a separate locating pin component with a locating feature, distinct from the seal body's air-tight interface. This allows the locating bore in the seal to have more generous tolerances since it only needs to accommodate the locating feature, while the air-tight interface tolerances remain tight but are not compounded with locating requirements.
Solution Approach 2:
The locating pin acts as an intermediary element between the housing and the seal. It provides the locating function through its locating feature that engages with the locating bore, thereby decoupling the locating requirements from the air-tight interface requirements and allowing independent optimization of both.
3Ease of operation
If heating is applied to ease the snap-fit during blind assembly, then ease of assembly is improved, but assembly time and energy consumption increase
Solution Approach 1:
The locating pin is pre-installed in the housing before the seal assembly. The locating feature on the pin protrudes into the seal's locating bore, establishing the correct position and orientation of the seal in advance. This preliminary action eliminates the need for complex blind alignment during final assembly.
Solution Approach 2:
The locating feature on the locating pin and the locating bore on the seal are designed to self-align during assembly. The geometric relationship between these features provides natural guidance that facilitates easy assembly without requiring external heating or other energy-intensive processes.
Data Source
AI summary
An assembly includes a case structure, a seal interfacing with the case structure, a first pin, and a main pin hole on one of the seal and the case structure. The first pin extends through the main pin hole and is fixed relative to the other of the seal and the case structure. The assembly also includes a second pin and a secondary pin hole on one of the seal and the case structure. The second pin extends through the secondary pin hole. A cross-sectional gap area between the second pin and the secondary pin hole is greater than a cross-sectional gap area between the first pin and the main pin hole. Also included is a bolt hole on one of the seal and the case structure. The bolt hole is circumferentially located between the main pin hole and the secondary pin hole.