Heat Exchanger Bore Plug Geometry for Full Gasket Seating
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Solution Overview
Problem
Conventional sealing devices for heat exchanger bores, such as those in air cooler equipment, face issues with gasket centering and seating, leading to potential leakage due to conical or cylindrical transition walls that do not ensure full contact between the gasket and the plug, resulting in gaps and reduced sealing effectiveness.
Innovation Solution
A sealing device with a bolt-type plug and annular gasket featuring a radial annular contact surface and an axial annular contact surface, including a circumferential groove on the axial annular contact surface, which allows for complete seating of the gasket without reducing the contact width, ensuring perfect sealing without complex machining operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conical transition wall is used to center the gasket, then the gasket can be positioned on the plug, but full contact between the gasket and plug head is not achieved, creating leakage points
Solution Approach 1:
The transition wall is segmented into two distinct functional surfaces: a conical portion for initial gasket positioning and orientation, and a cylindrical portion for providing the centering shoulder that ensures full contact between the gasket and plug head. This segmentation allows each surface to perform its specific function optimally without compromise.
Solution Approach 2:
The solution transitions from a single conical surface (one-dimensional taper) to a two-stage geometry that adds a cylindrical dimension. This dimensional change creates a proper centering shoulder that constrains the gasket radially while maintaining full contact with the plug head surface, eliminating the leakage issue.
2Reliability
If a cylindrical transition wall is used to center the gasket, then full contact between gasket and plug head can be achieved, but manufacturing complexity increases due to root transition radius requirements
Solution Approach 1:
The transition wall is divided into conical and cylindrical segments, where the conical portion can be easily machined using standard tapering operations, and the cylindrical portion provides the necessary centering function. This segmentation simplifies manufacturing compared to attempting to machine a perfect cylindrical transition with zero root radius.
Solution Approach 2:
The conical portion of the transition wall provides sufficient surface area for easy machining and gasket approach, while the cylindrical portion at the root provides the precise centering function. Each local region of the transition wall has optimized geometry for its specific function, balancing manufacturability with sealing performance.
3Manufacturing precision
If a groove is added to accommodate the gasket edge, then seating can be improved, but the contact surface width is reduced, affecting sealing capability
Solution Approach 1:
Instead of using a groove (which removes material and reduces contact area), the solution uses a cylindrical surface extension that adds a centering shoulder dimension. This allows the gasket to be properly seated and centered without reducing the radial width of the contact surface between the gasket and plug head.
Data Source
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AI summary
A sealing device (10) for bores, in particular bores (12) obtained on a header portion (14) of a heat exchanger, the sealing device (10) comprising: at least one bolt-type plug (16), which is provided with a head (18) and with a substantially cylindrical shank (20), wherein the shank (20) has a threaded cylindrical surface (22) which is substantially parallel to a central rotation axis (A) of the plug (16) and wherein the plug (16) is designed to be inserted into a corresponding bore (12) in a threaded coupling; and at least one annular gasket (24), which is provided with a central through hole (26) having a predefined internal diameter (B), wherein the gasket (24) is designed to be axially inserted around the shank (20) to make seal between the head (18) of the plug (16) and the bore (12). The plug (16) is provided with at least one annular seat (28) for accommodating the gasket (24). The seat (28) is arranged at a root connection between the head (18) and the shank (20) of the plug (16). The seat (28) comprises: a radial annular contact surface (30) which is substantially flat in the radial direction, which is obtained on a portion of the head (18) facing the shank (20) and which is substantially perpendicular to the central rotation axis (A), wherein the radial annular contact surface (30) is designed to be in contact with a radially oriented annular contact portion (32) of the gasket (24); and an axial annular contact surface (34) which is substantially flat in the axial direction, which is obtained on a root portion of the shank (20) at the radial annular contact surface (30) and which is substantially parallel to the central rotation axis (A), wherein the axial annular contact surface (34) has an internal diameter (C) which is substantially equal to the internal diameter (B) of the central through hole (26) of the gasket (24), and wherein the axial annular contact surface (34) is designed to form an axial centering shoulder for the gasket (24). The axial annular contact surface (34) is provided with at least one circumferential groove (38) having an internal diameter (D) which is smaller than the internal diameter (C) of the axial annular contact surface (34).