Stacked Piston Ring Assembly for Circumferential Shift Control
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Solution Overview
Problem
The existing piston rings suffer from stress concentration and fatigue failure due to the high-pressure side ring shifting circumferentially, leading to increased clearance and reduced fluid-tightness, as the low-pressure side ring is not restricted from rotating, causing uneven pressure distribution.
Innovation Solution
The piston ring design includes low-pressure and high-pressure side rings with rotation restriction parts, ensuring they remain fixed in the circumferential direction, maintaining consistent clearance and preventing stress concentration by restricting the rotation of both rings relative to the piston.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the low-pressure side ring is allowed to move freely in the circumferential direction, then the ease of operation is improved, but the reliability deteriorates due to stress concentration and fatigue failure
Solution Approach 1:
The patent applies local quality by providing rotation restriction parts at specific locations on the piston ring, allowing circumferential movement in most areas while restricting rotation at critical points. The restriction parts are strategically positioned to prevent stress concentration without completely eliminating circumferential movement capability.
Solution Approach 2:
The patent implements a dynamic solution where the piston ring can move circumferentially within certain limits but is restrained from excessive rotation. The rotation restriction parts provide a balanced system that allows necessary movement for operation while preventing harmful stress concentration through controlled restriction.
2Reliability
If the protrusion is inserted into the abutment with tight fit, then the fluid-tightness is improved, but the device complexity increases due to additional rotation restriction parts
Solution Approach 1:
The patent merges the fluid-tightness function with the rotation restriction function into a single integrated structure. The protrusion and abutment geometry is designed to provide both sealing and rotational restraint simultaneously, eliminating the need for separate complex restriction mechanisms while maintaining fluid-tightness.
Solution Approach 2:
The patent applies local quality by creating specific geometric features on the protrusion and abutment surfaces that provide both sealing contact and rotational restriction. The local geometry is optimized to achieve dual functions without adding overall structural complexity.
Data Source
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AI summary
Provided is a piston ring (20) including: a low-pressure side ring (21) having a low-pressure side abutment (21a); and a high-pressure side ring (22) having a high-pressure side abutment (22a), the low-pressure side ring (21) and the high-pressure side ring (22) are arranged stacked in a direction along the axis (X) so that the high-pressure side ring (22) is closer to a fluid to be compressed, a low-pressure side rotation restriction part configured to restrict rotation in the circumferential direction (CD) relative to the piston is formed to the low-pressure side ring (21), a high-pressure side rotation restriction part (22b) configured to restrict rotation in the circumferential direction (CD) relative to the piston and a low-pressure side protrusion (22c) protruding toward the low-pressure side ring (21) and inserted in the low-pressure side abutment (21a) are formed to the high-pressure side ring (22), and the low-pressure side protrusion (22c) is inserted in the low-pressure side abutment (21a) with clearances being provided in both sides in the circumferential direction (CD) between the low-pressure side ring (21) and the low-pressure side protrusion (22c).