Layered Secondary Seal Structure for Non-Contact Gap Sealing
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Solution Overview
Problem
Existing seals for circumferential gaps between rotating machine components in gas turbines face reliability issues due to complex designs and manufacturing inaccuracies, leading to incomplete sealing and increased assembly complexity.
Innovation Solution
A seal system comprising a main seal with a shoe and a secondary seal with layered metal sheets, where movable sheets of varying widths overlap to form a non-contact sealing system without additional spring systems, reducing friction and assembly complexity, and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex secondary sealing system with spring systems and intermediate plates is used, then the axial gap can be sealed, but the reliability decreases due to manufacturing inaccuracies and component distortion
Solution Approach 1:
The secondary seal is divided into multiple layers of metal sheets (first layer, second layer, third layer) with different configurations. Each layer segments the sealing function, allowing the system to accommodate axial gap variations without requiring complex spring systems or intermediate plates. The segmented structure distributes mechanical stresses and reduces the impact of manufacturing inaccuracies on overall sealing performance.
Solution Approach 2:
The invention transitions from a single-plane sealing approach to a multi-layered axial stacking configuration. By arranging metal sheets in multiple layers along the axial direction with overlapping edges, the sealing system gains an additional dimensional degree of freedom to accommodate axial displacements and gap variations, eliminating the need for complex mechanical compensation mechanisms.
2Adaptability or versatility
If thin metal sheets are used for the secondary seal, then the design can accommodate axial movement, but manufacturing inaccuracies and temperature influence cause distortion and jamming
Solution Approach 1:
The overlapping edge design of the metal sheets creates inherent clearance spaces between adjacent layers before any distortion occurs. This pre-built tolerance buffer accommodates manufacturing variations and thermal expansion without causing jamming. The layered structure with overlaps provides a cushioning effect that absorbs dimensional deviations from manufacturing inaccuracies.
Solution Approach 2:
The secondary seal employs a composite structure consisting of multiple metal sheet layers with different configurations (some with overlaps, some without). This composite arrangement combines the flexibility of thin sheets with the stability of overlapping joints, creating a system that is both adaptable to axial movement and resistant to distortion from manufacturing inaccuracies and thermal effects.
3Reliability
If additional spring systems and intermediate plates are included in the secondary seal, then axial gap sealing is achieved, but assembly complexity and manufacturing costs increase
Solution Approach 1:
The invention extracts and eliminates the intermediate plate and additional spring systems from the secondary seal design. By using only the layered metal sheet structure with overlapping edges, the system achieves axial gap sealing without these additional components. This extraction simplifies the manufacturing process, reduces assembly steps, and lowers production costs while maintaining sealing functionality.
Solution Approach 2:
The invention merges the functions of multiple components (spring systems, intermediate plates, and metal sheets) into a single integrated layered metal sheet structure. The overlapping edges of the metal sheets simultaneously provide mechanical support, axial movement accommodation, and sealing functionality, eliminating the need for separate components and simplifying both manufacturing and assembly processes.
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
The solution improves the reliability and simplifies the assembly of the seal, reducing manufacturing costs and testing requirements while maintaining high-temperature resistance and surface quality, ensuring effective sealing without jamming or distortion.
Implementation Method 1
at least one spring element, which supports the shoe on one of the machine components in such a way that radial movement of the shoe is possible in response to the application of fluid pressure to the shoe
Implementation Method 2
Two components, an intermediate plate and a cover, are provided so that both spring systems, that of the shoe and that of the secondary seal, can run parallel with little friction
Data Source
Figure 1~3
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Figure 7~9
AI summary
The invention relates to a seal (2) for sealing a circumferential gap between two machine components, wherein one of the machine components is rotatably mounted relative to the other machine component in the axial direction (A), comprising: a main seal (4) with at least one shoe (6) for producing a non-contact seal between the machine components and with at least one spring element (8) which supports the shoe (6) on one of the machine components in such a way that a radial movement (R) of the shoe (6) is possible in response to the application of fluid pressure to the shoe (6), and a secondary seal (12) which seals the spring element (8) in the axial direction (A), wherein the secondary seal (12) has at least two layers (14, 20) which adjoin each other in the axial direction (A).With a view to increasing the reliability of the functionality, it is provided that: - the layers (14, 20) each contain at least two radially adjacent sheets (16, 18, 22, 24), - in each layer, one of the sheets is fixed (16, 22) and the other sheet (18, 24) is movably mounted by being attached to the shoe (6), wherein - two movable sheets (24, 30) of each pair of immediately adjacent layers (14, 20), viewed in the radial direction (R), have different widths, wherein the wider of the two movable sheets (24) is combined (22) with a thinner, fixed sheet (22) to form layer (20), and the thinner (30) of the two movable sheets (18) is combined (16) with a wider, fixed sheet (16) to form layer (14), and - the wider movable sheet (24) of one layer (20) the wider fixed sheet (16) overlaps the other layer (14) in radial direction (R).