Adhesive-Positioned Seal Shoes for Tight-Clearance Assembly
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Solution Overview
Problem
In gas turbine engines, the tight build gap clearance between non-contact seal shoes and seal lands often results in damage during assembly due to manufacturing and assembly tool tolerances, leading to seal malfunction.
Innovation Solution
The use of a cyanoacrolate adhesive is applied between seal components, allowing the shoes to be secured in a specific position, which then opens the clearance between the seal and the rotating member, enabling assembly and balancing of the HALO seal assembly, with the adhesive burning off at elevated temperatures to allow proper operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tight build gap clearance is used between seal shoes and seal land, then sealing performance is improved, but damage to seal shoes during assembly increases
Solution Approach 1:
The adhesive is applied to the seal shoes before assembly to pre-position them at the correct location and orientation. This preliminary positioning ensures that the shoes are correctly placed before the tight clearance assembly occurs, preventing damage while maintaining sealing performance
Solution Approach 2:
The adhesive acts as an intermediary substance between the seal shoes and the seal land, providing temporary bonding during assembly. This intermediary allows the shoes to be held in the correct position without requiring forceful installation that could cause damage to the tight-tolerance components
2Manufacturing precision
If adhesive is applied to secure seal shoes, then assembly precision is improved, but complexity of assembly process increases
Solution Approach 1:
The adhesive is applied in advance to the seal shoes or seal land before the actual assembly operation. This preliminary application of adhesive simplifies the assembly process by eliminating the need for complex positioning mechanisms or specialized assembly tools, while still achieving high assembly precision through the bonding action
Solution Approach 2:
The mechanical system of precise positioning and alignment during assembly is replaced with a chemical bonding system using adhesive. This substitution reduces assembly complexity by replacing complex mechanical alignment procedures with a simpler application of adhesive that automatically bonds components in the correct position
3Strength
If adhesive is used to hold seal shoes in position, then structural integrity is improved, but thermal resistance decreases
Solution Approach 1:
The adhesive undergoes a phase transition from solid to gas through decomposition at elevated temperatures. This phase transition allows the adhesive to maintain structural integrity during assembly and operation at normal temperatures, while automatically decomposing at high temperatures to prevent thermal damage to the seal components
Solution Approach 2:
The adhesive's physical and chemical parameters are selected to change at specific temperature thresholds. The adhesive maintains its bonding properties at assembly and operating temperatures but decomposes at elevated temperatures, providing temperature-dependent functionality that protects the seal while maintaining structural integrity when needed
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 method ensures secure assembly and operation of the seal by maintaining the seal shoes in the desired position during assembly and operation, minimizing travel and stress while allowing for proper clearance and structural integrity.
Implementation Method 1
The adhesive may be a cyanoacrolate adhesive
Implementation Method 2
the adhesive burning off at elevated temperatures to allow proper operation
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A seal comprises a support ring (230), a shoe (232) coupled to the support ring via an arm (234), and an adhesive (540) disposed between the shoe and the support ring, wherein the adhesive secures the shoe with respect to the support ring. A method for assembling a seal arrangement comprises the steps of applying an adhesive to a seal and applying a force to a shoe of the seal.