Piston Ring Varying Apex Line Hydrodynamic Oil Distribution
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Solution Overview
Problem
Conventional piston rings in large-displacement two-stroke engines face challenges in achieving uniform lubrication and minimizing oil consumption and leakage gas passage due to inadequate pressure gradients in the circumferential direction, leading to inefficient lubrication and increased oil consumption.
Innovation Solution
A piston ring with a convex crowned running surface featuring a varying apex line in the axial direction, creating hydrodynamic pressures that redistribute lubricating oil and enhance its uniform distribution, while eliminating recesses or holes to reduce oil consumption and leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional piston ring design with uniform running surface is used, then manufacturing is simple, but lubrication distribution is non-uniform and oil consumption increases
Solution Approach 1:
The running surface is designed with locally varying apex line positions in the axial direction, creating different surface profiles at different circumferential locations. This local variation in surface geometry generates hydrodynamic pressure gradients that redirect oil flow to areas needing lubrication, reducing overall oil consumption while maintaining simple manufacturing processes.
Solution Approach 2:
The apex line position varies dynamically around the circumference, creating a dynamic hydrodynamic pressure distribution during piston operation. This dynamic pressure field actively redistributes lubricating oil throughout the circumferential direction, ensuring uniform lubrication with reduced oil quantity.
2Stress or pressure
If conventional piston ring design is used, then structure is simple, but pressure gradient for oil distribution is insufficient
Solution Approach 1:
The running surface incorporates a crowned profile with a varying apex line that creates curved hydrodynamic pathways. This curvature generates centrifugal and hydrodynamic pressure gradients during piston motion, forcing lubricating oil to distribute uniformly in the circumferential direction without requiring complex additional structures.
3Reliability
If more lubricating oil is supplied, then lubrication quality improves, but oil consumption and costs increase
Solution Approach 1:
The invention utilizes hydrodynamic principles by designing the running surface to generate pressure gradients in the lubricating oil during piston operation. These hydrodynamic pressures actively pump and redistribute the oil circumferentially, ensuring reliable lubrication with minimal oil supply through fluid dynamics rather than excessive quantity.
4Ease of manufacture
If uniform running surface is used, then manufacturing is easy, but oil redistribution in circumferential direction is poor
Solution Approach 1:
The apex line position parameter is varied continuously or periodically around the circumference of the running surface. This parameter variation creates corresponding variations in hydrodynamic pressure that actively redistribute lubricating oil uniformly in the circumferential direction, while the overall surface profile remains manufacturable using conventional polishing and grinding techniques.
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 solution ensures consistent lubrication, minimizes leakage gas passage, and reduces oil consumption by effectively redistributing lubricating oil in the circumferential direction, achieving optimal sealing and oil usage.
Implementation Method 1
A running surface of the piston ring designed in this way causes hydrodynamic pressures (in particular varying with the axial position of the apex) to build up or occur in the direction of rotation during operation. These hydrodynamic pressures result in pressure gradients that induce lubricating oil flows
Data Source
Figure 1(a)~1(c)
Figure 2(a)~2(b)
Figure 3~4
AI summary
The invention relates to a piston ring (1) with an outer running surface (3), two flanks (5, 6) and an inner circumferential surface (7). The running surface (3) has a profile. The profile of the running surface is essentially convexly spherical (10) and has an apex (B1). The axial position of the apex (B1) varies periodically in the circumferential direction.