Cambered Piston Ring Profile to Prevent Lock-End Leakage
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Solution Overview
Problem
Conventional piston rings in large internal combustion engines experience leakage due to pressure-induced opening of the locking ends, leading to damage and reduced durability, especially in low-speed engines with high combustion pressures.
Innovation Solution
A piston ring design featuring a cambered profile with a pivot line and a flat section, combined with a phosphate-based coating, to enhance sealing and durability by minimizing outward pressure on the cylinder liner and reducing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional piston rings are used with locking ends, then the piston ring can be assembled and sealed, but the locking ends open under pressure causing leakage and damage
Solution Approach 1:
The invention applies a cambered profile to the piston ring cross-section, where the radial width varies along the axial direction with maximum width at the center and reduced width at the edges. This curved geometry creates a mechanical advantage that prevents the locking ends from opening under pressure, as the cambered shape distributes the pressure loads more effectively and maintains the closed position of the locking ends during operation.
Solution Approach 2:
The invention changes the geometric parameters of the piston ring by introducing a cambered profile with specific curvature radius (R = 50-150 mm) and controlling the radial width distribution. This parameter change transforms the rigid rectangular cross-section into a flexible cambered shape that can deform elastically under pressure to maintain sealing while preventing locking end opening.
2Ease of manufacture
If the piston ring locking ends are designed to fit together, then assembly is possible, but wear and damage occur reducing durability
Solution Approach 1:
The invention applies different properties to different parts of the piston ring by coating only the running surface (outer cylindrical surface) with a phosphate-based coating while leaving the locking ends and other areas uncoated or differently treated. This local quality approach provides wear protection where needed (running surface) while maintaining the mechanical integrity and assembly characteristics of the locking ends.
Solution Approach 2:
The invention creates a composite structure by combining the base piston ring material (cast iron or steel) with a phosphate-based coating layer on the running surface. This composite structure provides both the mechanical strength and sealing properties of the metal and the wear-resistant, low-friction properties of the phosphate coating, thereby extending service life.
3Reliability
If the piston ring runs against the cylinder liner, then sealing is achieved, but wear occurs on both surfaces
Solution Approach 1:
The invention applies a phosphate-based coating specifically to the running surface of the piston ring that contacts the cylinder liner. This local coating provides a low-friction, wear-resistant layer that reduces wear on both the piston ring and cylinder liner while maintaining the sealing function. The coating creates a protective barrier that prevents direct metal-to-metal contact.
Solution Approach 2:
The phosphate-based coating acts as an intermediary layer between the piston ring metal and the cylinder liner metal. This intermediate layer reduces direct contact and friction between the two metal surfaces, thereby reducing wear on both components while still allowing the piston ring to seal against the cylinder liner effectively.
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 maintains gas-tight sealing and extends the lifespan of the piston ring by minimizing wear and preventing damage to the cylinder liner, even under high-pressure conditions.
Implementation Method 1
The outer surface of the piston ring can be coated, in particular with a phosphate-based coating
Data Source
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AI summary
A piston ring (100) for a piston of a reciprocating internal combustion engine comprises a ring section (1) and a lock section (2). The lock section (2) comprises a circumferential parting line (7) in a first axial parting line distance (PaT) from a top surface (T) of the piston ring (100) and a second axial parting line distance (PaB) from the bottom surface (B) of the piston ring (100). Further the piston ring (100) comprises a cambered profile (10) with a circumferential pivot line (8) having a first axial pivot line distance (PiT) from the top surface (T) and a second axial pivot line distance (PiB) from the bottom surface. According to the invention, the axial distance (9) between the circumferential parting line and the pivot line is smaller than 20%, preferably smaller than 10%, of the axial width of the piston ring. Alternatively or in addition to a distinct pivot line, the cambered profile (10) can comprise a most protruding, axially extending, flat section (14). Then, the flat section (14) includes the circumferential parting line (7).