Gas Seal Ceramic-to-Steel Attachment via Elastic Fixing Element
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Solution Overview
Problem
The challenge lies in efficiently and simply attaching ceramic components to steel components in gas seals, as their differing thermal expansion coefficients complicate a straightforward connection, making existing attachment methods cumbersome and space-consuming.
Innovation Solution
A modular gas seal design featuring a ceramic sliding sleeve and ring, with an elastic fixing element, such as a helical spring or garter spring, that can be inserted tangentially into a curved cavity, providing axial and radial deformability to securely fasten the sliding sleeve to the stator while accommodating thermal expansion differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ceramic components are attached to steel components using conventional methods, then the connection is secure, but the attachment becomes cumbersome and space-consuming due to thermal expansion differences
Solution Approach 1:
The gas seal is designed as a modular insert (cartridge) that can be easily replaced as a complete unit. This segmentation allows the complex ceramic-to-steel attachment to be pre-assembled and tested separately, then installed as a single module, greatly simplifying the manufacturing and replacement process while maintaining secure connections despite thermal expansion differences
Solution Approach 2:
The sliding sleeve is inserted into a circumferentially extending curved cavity in the stator, creating a nested structure. The fixing element is then inserted tangentially into this cavity to secure the sliding sleeve. This nesting approach allows compact arrangement of components with different thermal expansion coefficients while maintaining secure attachment without requiring complex external fastening structures
2Stability of the object's composition
If the gas seal is designed as a fixed rigid structure, then stability against vibrations is achieved, but the thermal expansion mismatch between ceramic and steel causes stress and potential failure
Solution Approach 1:
The fixing element is designed with elastic properties, allowing it to deform under thermal stress. This change in mechanical parameter (from rigid to elastic) enables the connection to accommodate thermal expansion differences between ceramic sliding rings and steel components while maintaining structural stability and vibration resistance during operation
Solution Approach 2:
The fixing element transitions from a static rigid connection to a dynamic elastic connection that can adapt to changing thermal conditions. The elastic element can deform and recover, providing continuous accommodation of thermal expansion while maintaining stable fixation, thus improving reliability under thermal cycling conditions
3Manufacturing precision
If a sliding sleeve is used to guide the stationary sliding ring, then radial guidance is improved, but the attachment of the sliding sleeve to the stator becomes more complex
Solution Approach 1:
The sliding sleeve is inserted into a curved cavity in the stator, creating a nested structure that provides radial guidance. The fixing element is then inserted tangentially into the same cavity to secure the sliding sleeve. This nested arrangement achieves precise radial guidance while keeping the attachment structure compact and relatively simple, avoiding the need for separate complex fastening mechanisms
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 allows for easy assembly and replacement of gas seals, ensuring stability against vibrations and maintaining sealing integrity despite axial flexibility, effectively addressing the thermal expansion mismatch between ceramic and steel components.
Implementation Method 1
the fixing element is also designed to be deformable in the radial direction... Elastic deformation of the fixing element provides the additional advantage of elasticity of the gas seal
Implementation Method 2
the fixing element can be designed, in particular, as a helical spring and, more preferably, as a coil spring or worm spring
Implementation Method 3
The thermal expansion of these ceramic materials is approximately 3.5 x 10−6 m/K per meter. In comparison, the thermal expansion of steel, the material typically used in conjunction with these ceramic seals, is approximately 11 x 10−6 m/K per meter
Data Source
Figure 1
AI summary
The invention relates to a gas seal, in particular a dry gas seal, which extends in a circumferential direction (CDR) in an axis (X) and comprises a rotating slip ring (RSR) and a stationary slip ring (SSR), the stationary slip ring (SSR) being axially movable. The gas seal (GDS) comprises a slip sleeve (SLV), the slip sleeve (SLV) guiding the stationary slip ring (SSR) in the axial movement direction by means of a first sliding face (SSF1) on a second sliding face (SSF2). The gas seal is characterised in that the slip sleeve (SLV) is fastened to a stator (STS) of the gas seal (GDS), wherein the slip sleeve (SLV) has a first recess (RZ1) extending in the circumferential direction (CDR), and the stator (STS) has a second recess (RZ2), opposite the first recess (RZ1) in the region of the fastening, extending in the circumferential direction (CDR), such that the first recess (RZ1) and the second recess (RZ2) define a common cavity (CAV) extending in the circumferential direction (CDR). In the cavity (CAV) there is an elongate fixing element (FXE) which at least partially fills the first recess (RZ1) and the second recess (RZ2) such that an unlimited axial relative movement is only possible when the fixing element (FXE) is radially deformed.