Non-Contact Seal Ring Window Openings for Tight Shaft Clearance
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Solution Overview
Problem
In gas turbine engines, the non-contact seal around rotating shafts often experiences reduced gap clearance due to assembly tolerances, leading to potential damage and malfunction as the seal shoes may be forced to contact the shaft, causing damage and malfunction.
Innovation Solution
A seal arrangement featuring a carrier ring, a seal ring with window openings and scalloped openings, and a melting element is used to secure the seal shoes in an outboard position, preventing contact with the shaft by applying heat and a force to move the melting element through the window openings into the gap between the seal and the shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tight build gap clearance is used for the non-contact seal, then the seal performance is improved, but the risk of seal shoe damage due to contact with the shaft increases
Solution Approach 1:
The patent applies preliminary action by pre-positioning the seal shoes in an outboard position using a melting element (such as wax or plastic) that is installed in the gap between the seal shoe and shaft during assembly. This preliminary positioning prevents the seal shoes from contacting the shaft during operation, even when tight build gap clearance is used for optimal seal performance. The melting element acts as a temporary spacer that maintains proper clearance until operational conditions cause it to melt away.
2Ease of manufacture
If assembly tolerances are considered, then the ease of manufacture is improved, but the gap clearance between seal and shaft is reduced or eliminated
Solution Approach 1:
The patent employs an intermediary approach by introducing a melting element as a mediator between the seal shoe and the shaft. This melting element compensates for assembly tolerances and ensures adequate gap clearance is maintained during assembly and initial operation. The melting element can be easily installed through window openings in the seal ring, allowing assembly personnel to accommodate tolerance variations without requiring precision machining, while still ensuring the seal shoe does not contact the shaft.
3Reliability
If the seal shoes are forced to contact the shaft, then the sealing effect is improved, but the seal malfunctions due to damage
Solution Approach 1:
The patent applies beforehand cushioning by using the melting element as a protective buffer between the seal shoe and the shaft. This cushioning element is installed in advance during assembly and prevents direct contact between the seal shoe and shaft, thereby protecting the seal shoe from damage while still allowing the seal to function effectively. The melting element absorbs any potential contact forces before they can reach the seal shoe, ensuring the seal maintains its integrity and continues to provide reliable sealing.
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 seal shoes remain in an outboard position, preventing damage and ensuring proper operation by maintaining a non-contact seal, thus enhancing the reliability and longevity of the seal assembly.
Implementation Method 1
a melting element is moved through the plurality of window openings to the non-contact seal
Implementation Method 2
applying heat to at least one of a carrier ring and a static support piece
Data Source
AI summary
A seal ring for a non-contact seal may comprise an annular body comprising a first side surface, a second side surface, an outer surface, and an inner surface, and a plurality of window openings disposed in the annular body. The plurality of window openings may be configured to provide access to the seal for installation of a melting member to secure the seal shoes in an outboard direction during installation.