Piston Ring Tread Conicity for Uniform Pivot Point
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Solution Overview
Problem
Existing piston rings with cross-sectional defects and varying twist angles lead to non-uniform pivot point positions, causing uneven hydrodynamic pressure distribution and potential collapse, resulting in issues like oil sliding and poor sealing behavior under gas pressure.
Innovation Solution
A piston ring design with varying tread conicities and crowning that start from the joint and increase in both circumferential directions, ensuring a uniform pivot point position over the circumference, minimizing the gas attack surface and optimizing sealing behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform running surface conicities or crowning are provided in piston rings with cross-sectional defects, then the manufacturing is simplified, but the pivot point position becomes non-uniform around the circumference leading to uneven hydrodynamic pressure distribution
Solution Approach 1:
The patent applies local quality by providing different running surface conicities at different locations around the circumference. Specifically, the running surface has a first conicity in the region with cross-sectional defect and a second conicity in the region without defect, where the two conicities are different. This local differentiation compensates for the twist angle variations caused by cross-sectional defects, ensuring uniform pivot point positioning around the circumference while maintaining manufacturing feasibility.
2Reliability
If cross-sectional defects are introduced to achieve proper piston ring seating, then the piston ring rests correctly on the cylinder wall, but the solution becomes technically complex and expensive
Solution Approach 1:
The patent applies parameter changes by modifying the running surface conicity parameter rather than introducing complex cross-sectional defects. By adjusting the conicity values (first conicity and second conicity) based on the presence or absence of cross-sectional defects, the patent achieves proper piston ring seating and uniform pivot point positioning through a simpler geometric parameter modification, reducing manufacturing complexity while maintaining seating accuracy.
3Ease of operation
If the piston ring has a joint forming a discontinuity, then the piston ring can be installed, but the twist angle changes in the circumferential direction affecting pivot point uniformity
Solution Approach 1:
The patent addresses the joint-induced twist angle variation by applying local quality through differentiated running surface conicities. The running surface is designed with specific conicity values in different circumferential regions, particularly accounting for the joint location. This local conicity adjustment compensates for the twist angle changes caused by the joint, ensuring that the pivot point maintains a substantially uniform position around the circumference despite the installation discontinuity.
Data Source
Figure 1~2
Figure 3
AI summary
Disclosed is a piston ring (1) comprising a main body having a sliding surface (2), an inner peripheral surface and upper and lower flanks extending between said surfaces, wherein the main body is provided with a gap and in particular in the region of its inner peripheral surface has a cross-sectional interruption, and wherein, viewed in the peripheral direction, the sliding surface (2) is provided with varying conicities (α) and/or crownings such that in the region of the gap the conicity (α) and/or crowning is/are less than in the diametrically opposite rear of the ring.