Non-Contact Seal Ring Access Windows for Build Gap Assembly
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Solution Overview
Problem
In gas turbine engines, non-contact seals around rotating shafts often malfunction due to tight build gap clearance caused by assembly tolerance issues, leading to damage and malfunction.
Innovation Solution
A seal arrangement with a seal ring and melting elements is used, where the melting elements hold the seal shoes in an outboard position during installation to maintain a gap and prevent contact with the shaft, and are designed to melt and allow movement during operation, ensuring proper sealing without physical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tight build gap clearance is used in non-contact seal assembly, then sealing performance is improved, but assembly tolerance variations cause gap reduction or elimination leading to seal shoe damage
Solution Approach 1:
The patent applies preliminary action by positioning the seal shoes in a predetermined outboard position during assembly using temporary retaining structures (such as retainers or clips) that hold the shoes away from the shaft. This preliminary positioning ensures the gap is maintained during installation, preventing damage before the seal begins operation. Once installed, these temporary retaining structures are removed, allowing the seal to function normally with the shoes in their operational position.
Solution Approach 2:
The patent uses an intermediary component (retaining structure or positioning device) that temporarily holds the seal shoes in the correct position during assembly. This intermediary element mediates between the tight build gap clearance requirement and the need to prevent shoe contact during installation. The retaining structure acts as a temporary spacer or support that ensures proper gap clearance is maintained during the critical assembly phase, then is removed once installation is complete.
2Ease of operation
If access window openings are added to seal ring, then ease of installation and maintenance is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the seal ring into sections with access window openings that provide pathways for installing and maintaining the seal shoes. These openings segment the otherwise continuous seal ring structure, allowing access to internal components without requiring complete disassembly. The segmented design enables technicians to reach through the openings to position retainers, install shoes, or perform maintenance while the seal remains installed on the shaft.
Solution Approach 2:
The patent extracts or removes material from the seal ring to create access window openings. This taking out approach creates passages through the seal ring body that provide access to the seal shoes and retaining structures. By extracting material to form these windows, the design enables easier installation and maintenance operations while maintaining the overall integrity and sealing function of the seal ring.
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 solution ensures the non-contact seal maintains its functionality by preventing damage from assembly-induced contact and allows for effective sealing across pressure gradients, enhancing the reliability and longevity of the seal.
Implementation Method 1
The melting element is configured to melt in response to heat from engine operation
Implementation Method 2
a non-contact seal configured to prevent fluid leakage across a pressure gradient between a high pressure side and a low pressure side of the non-contact seal
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A seal ring (216) for a non-contact seal (214) may comprise an annular body comprising a first side surface (304), a second side surface, an outer surface (306), and an inner surface (308), and a plurality of window openings (240) disposed in the annular body. The plurality of window openings (240) may be configured to provide access to the seal (214) for installation of a melting member (250) to secure the seal shoes (232) in an outboard direction during installation.