Cambered Piston Ring Lock Geometry for Gas-Tight Sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional piston rings in large reciprocating internal combustion engines, particularly those used in low-speed two-stroke engines, suffer from leakage due to pressure-induced opening of the locking ends, leading to damage and reduced durability, especially in dual-fuel or Otto-cycle engines.
Innovation Solution
A piston ring design featuring a cambered profile with a pivot line and a flat section, combined with a precise gap and lapping process, ensures a gas-tight seal and enhanced durability by minimizing outward pressure on the cylinder liner, using a coating for added protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional piston rings with rectangular cross-section are used, then manufacturing is simple, but leakage occurs due to pressure-induced opening of locking ends
Solution Approach 1:
The piston ring employs a cambered profile with a curved outer surface instead of a flat rectangular cross-section. The cambering creates a pivot line that allows the ring to rotate and seal effectively against the cylinder wall, preventing leakage while maintaining structural integrity under pressure.
Solution Approach 2:
The piston ring is divided into a lock section with a tongue and a ring section with a recess, creating a segmented locking mechanism. This segmentation allows the ring to maintain a gas-tight seal while accommodating the complex cambered profile, resolving the contradiction between sealing reliability and structural simplicity.
2Ease of manufacture
If the recess is open towards the radially outer side, then assembly is easier, but pressure causes the locking ends to open leading to damage
Solution Approach 1:
The invention changes the geometric parameters of the locking mechanism by positioning the circumferential parting line close to the pivot line (within 20% of axial width). This parameter adjustment ensures that the locking ends remain closed under pressure while maintaining ease of assembly, as the recess remains open towards the radially outer side.
Solution Approach 2:
The design converts the potential harm of pressure-induced opening into a benefit by strategically positioning the parting line near the pivot line. This ensures that pressure forces the locking ends to remain closed, transforming the harmful effect into a sealing mechanism that enhances durability.
3Ease of manufacture
If the circumferential parting line is positioned far from the pivot line, then manufacturing is easier, but sealing effectiveness decreases
Solution Approach 1:
The invention optimizes the position of the circumferential parting line by placing it within 20% of the axial width from the pivot line. This parameter change ensures that the parting line remains close to the sealing contact point, maintaining high sealing effectiveness while still allowing for practical manufacturing processes.
4Adaptability or versatility
If the piston ring operates in dual-fuel or Otto-cycle engines, then versatility is improved, but leakage and damage increase due to pressure-induced opening
Solution Approach 1:
The invention adjusts the geometric parameters of the piston ring, specifically positioning the parting line close to the pivot line and implementing a cambered profile. These parameter changes enable the piston ring to maintain reliable sealing under the high pressure conditions of dual-fuel and Otto-cycle engines, enhancing versatility without sacrificing sealing reliability.
Data Source
Figure 1
Figure 2
Figure 3
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).