Piston Ring Groove for Uniform Lubrication
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Solution Overview
Problem
Conventional piston rings in large-displacement two-stroke marine engines face challenges in achieving uniform lubrication and minimizing oil consumption and leakage gas passage due to lack of pressure gradients in the circumferential direction.
Innovation Solution
A piston ring design featuring a wavy groove on its running surface, which creates hydrodynamic pressures and redistributes lubricating oil, ensuring uniform lubrication and minimizing leakage by adapting to varying twist and torsion across the circumference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional piston ring design is used, then manufacturing cost is low and structure is simple, but lubricating oil distribution in circumferential direction is non-uniform and oil consumption is high
Solution Approach 1:
The piston ring running surface incorporates a circumferential groove with a specific curved profile shape. This curved groove profile creates hydrodynamic pressure gradients that actively redistribute lubricating oil along the circumferential direction, ensuring uniform oil distribution and reducing overall oil consumption while maintaining effective lubrication.
Solution Approach 2:
The groove design utilizes hydrodynamic principles by creating pressure gradients through its curved profile. The groove acts as a hydraulic channel that redirects lubricating oil flow in the circumferential direction, using the motion of the piston ring to generate pressures that distribute oil uniformly across the running surface.
2Reliability
If conventional piston ring design is used, then structure is simple, but lubrication uniformity in circumferential direction is poor
Solution Approach 1:
The circumferential groove is designed with a specific curved profile rather than a straight or simple shape. This curvature is optimized to generate hydrodynamic pressure gradients that actively transport lubricating oil along the circumferential direction, ensuring uniform lubrication distribution while maintaining a relatively simple single-groove structure.
Solution Approach 2:
The groove profile parameters (depth, width, curvature radius, and longitudinal shape) are specifically optimized to create the desired hydrodynamic effects. By adjusting these geometric parameters, the groove generates appropriate pressure gradients that redistribute oil uniformly without requiring complex multi-groove or adjustable mechanisms.
3Manufacturing precision
If lubricating oil is injected with high pressure for fine spray, then wetting of cylinder liner is improved, but time required for oil distribution is increased
Solution Approach 1:
The circumferential groove utilizes the periodic reciprocating motion of the piston ring during engine operation to generate alternating hydrodynamic pressure gradients. This periodic action continuously pumps and redistributes lubricating oil along the circumferential direction during each stroke cycle, achieving uniform distribution without requiring extended time periods.
Solution Approach 2:
The groove design enables the piston ring to self-distribute lubricating oil using its own motion. The hydrodynamic pressure gradients generated by the groove profile during normal piston operation automatically redirect and redistribute oil in the circumferential direction, eliminating the need for additional active distribution mechanisms or extended distribution time.
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 achieves reduced lubricating oil quantity and improved distribution, ensuring sufficient lubrication and minimizing leakage gas passage while being cost-effective and adaptable to different engine conditions.
Implementation Method 1
During operation, hydrodynamic pressures can build up in the circumferential direction in the groove. These hydrodynamic pressures result in pressure gradients that cause lubricating oil flows and redistribution of the lubricating oil.
Implementation Method 2
The hydrodynamically caused redistribution of the lubricating oil leads to a reduction in the required quantity and a more uniform distribution of the lubricating oil fed or injected into the groove with respect to the circumferential direction.
Data Source
Figure 1~3
Figure 4A~6B
Figure 6C
AI summary
The invention relates to a piston ring for an internal combustion engine or for a compressor, in particular a piston ring comprising an exterior running surface (3), two flanks (5, 6), and an interior circumferential surface (7); the running surface (3) has a profiled section with a groove (2), said groove (2) being located between an upper portion (3') of the running surface and a lower portion (3") of the running surface in relation to the cross-section of the piston ring (1).