Overlapping Compression Ring Butt Seal for Abrasive Wear Control
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Solution Overview
Problem
Current compression rings in 2-stroke crosshead engines suffer from abrasive wear due to axial and radial gaps, leading to system failure, and their production is complex due to distortion during grinding, with thermal expansion complicating the manufacturing process.
Innovation Solution
A compression ring design featuring overlapping butt end regions with protrusions and recesses, incorporating wear elements made of low-wear resistance materials like copper or bronze, which shift parallel to each other to adjust to changes in butt play, minimizing wear and ensuring a gas-tight seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the axial and radial clearance of the butt is reduced to minimize wear, then the sealing performance improves, but the manufacturing complexity and reject rate increase due to distortion during grinding
Solution Approach 1:
The compression ring butt is divided into multiple segments with protrusions and recesses that overlap to form axial and radial seal surfaces. This segmentation allows each surface to be independently manufactured and positioned, reducing the need for high-precision grinding of the entire butt while maintaining effective sealing through the overlapping structure.
Solution Approach 2:
The protrusions and recesses are pre-formed on the butt ends before final assembly. This preliminary action allows the seal surfaces to be prepared in advance with controlled tolerances, reducing the need for complex post-grinding operations and minimizing distortion-related rejections during final manufacturing.
2Object-affected harmful factors
If the axial and radial clearance is made small to prevent abrasive wear, then the sealing effectiveness improves, but the production complexity increases due to grinding distortion
Solution Approach 1:
Wear elements are introduced as intermediary components between the overlapping butt surfaces. These wear elements can be replaced independently when worn, protecting the main ring structure from abrasive wear while allowing larger clearances. This mediator approach reduces the need for extremely tight tolerances in ring manufacturing.
Solution Approach 2:
The wear elements are designed as consumable components with lower material cost that can be replaced periodically. By using these disposable wear elements, the main compression ring structure can have larger, easier-to-manufacture clearances without suffering from abrasive wear, as the wear elements protect the permanent ring surfaces.
3Reliability
If thermal expansion is considered during operation, then the sealing reliability improves, but the manufacturing precision requirements increase due to distortion during grinding
Solution Approach 1:
The butt structure is designed to be dynamically adaptable through the overlapping protrusion-recess configuration. This design allows the butt surfaces to shift and adjust during thermal expansion and contraction cycles, maintaining sealing contact despite dimensional changes. The wear elements also provide dynamic compensation as they wear and are replaced, accommodating thermal variations without requiring extremely precise initial manufacturing.
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 design effectively minimizes wear and maintains a gas-tight seal by allowing the wear elements to systematically grind down, maintaining the nominal size and reducing the risk of system failure due to thermal expansion and abrasive wear.
Implementation Method 1
the thermal expansions, as they appear during the start-up and during load changes, must not lead to an increased wear or even a destruction of sealing structures
Implementation Method 2
the hot combustion gas transports particles from the combustion. If the axial and the radial clearance is greater than 0, this leads to a strong abrasive wear on the sealing surfaces of the two butt ends
Data Source
AI summary
A compression ring, has a ring running surface (2) on a first butt end region, a ring running surface (2′) on a second butt end region, a ring inner surface (4), a top ring flank surface (6) and a bottom ring flank surface (8), wherein the ring has overlapping first and second butt end regions. The first butt end region has at least one protrusion (10) in the circumferential direction, and the second butt end region has at least one recess (12) in the circumferential direction. The at least one protrusion (10) forms at least one axial and/or radial overlap surface, and the at least one recess (12) forms at least one parallel surface, which lies at least partially opposite to the axial and/or radial overlap surface in order to shift parallel to one another in response to a change of the butt play. At least one of the surfaces, which can be shifted parallel to one another, is provided with an axial wear element (14) and/or with a radial wear element (14′).