Piston Ring Symmetrical Butt Lock for Wear Compensation
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Solution Overview
Problem
Piston rings in dry-running compressors experience wear-related increases in clearance, leading to reduced sealing effectiveness and short operational lifespans, especially when compressing light gases like hydrogen, and existing solutions are costly, difficult to assemble, and prone to breakage.
Innovation Solution
A piston ring design featuring a one-piece sealing ring with a straight joint and a butt lock that extends over a controlled angular range, allowing for even material wear and maintaining sealing effectiveness through radial displacement of the butt lock, which is symmetrically designed to ensure balanced forces and reduce the risk of breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a one-piece straight joint seal ring is used, then the structure is simple and easy to manufacture, but wear increases the gap between butt ends leading to reduced sealing effect
Solution Approach 1:
The seal ring is divided into two functional segments: a sealing ring portion that contacts the cylinder and undergoes wear, and a butt lock portion that remains stationary and maintains sealing. The sealing ring can rotate independently within the butt lock, allowing the sealing surface to be periodically refreshed while the locking mechanism stays fixed, thus maintaining sealing effectiveness despite wear.
Solution Approach 2:
The patent introduces a dynamic element where the sealing ring portion can rotate relative to the butt lock portion. This rotation allows the sealing surface to be periodically renewed by bringing fresh surfaces into contact with the cylinder, compensating for wear without requiring replacement of the entire ring. The dynamic rotation mechanism is enabled by the clearance and geometric design of the butt lock.
2Reliability
If a twin ring design with L-shaped cover ring is used, then wear is compensated by elastic bending, but production costs increase and there is a risk of breakage
Solution Approach 1:
The patent merges the sealing function and the wear compensation function into a single integrated structure. The sealing ring with its specific geometric profile (including the radially extending portions and the arcuate outer surface) combines both sealing and wear compensation capabilities, eliminating the need for separate cover rings or complex twin ring assemblies.
Solution Approach 2:
The sealing ring incorporates flexible geometric features including an arcuate outer surface and radially extending portions that can elastically deform. This flexibility allows the ring to adapt to wear by rotating and redistributing contact pressures, providing wear compensation through elastic deformation of the ring's own structure rather than through separate compensating components.
3Reliability
If the butt lock leg parts extend over a large angular range, then sealing coverage is improved, but the risk of breakage increases during assembly
Solution Approach 1:
The patent applies different geometric characteristics to different portions of the sealing ring. The radially extending portions have specific angular extents optimized for sealing coverage, while the arcuate outer surface provides structural strength. The contact surfaces are localized to specific regions, allowing adequate sealing coverage without requiring the entire ring to be overly thick or rigid, thus reducing breakage risk.
Solution Approach 2:
The sealing ring features an arcuate outer surface that follows a circular arc, providing both sealing contact and structural strength. The curved geometry distributes stresses more evenly compared to straight edges, reducing stress concentration points that could lead to breakage during assembly or operation. The arcuate shape also naturally accommodates the radial forces experienced during compression.
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 provides long-term sealing performance, withstands high pressures, is cost-effective, and easy to assemble, with reduced material requirements and lower risk of damage during assembly, maintaining sealing effectiveness despite wear.
Implementation Method 1
The pressure difference across the piston ring causes a radially outward force to be applied to the butt lock
Implementation Method 2
the butt lock may wear out, but the butt lock due to the radially outward force and wear radially outwards
Data Source
AI summary
The piston ring (1) for a reciprocating compressor comprises: a one-part sealing ring (2) that extends in a peripheral direction (N) about a center (M) with an axial direction (H) and has an arcuate outer surface (2k), the sealing ring (2) having a butt joint with joint ends (21) and a gap (2a) that extends between the joint ends (21) in the peripheral direction (N); and a joint seal (3) for sealing the gap (2a), said joint seal (3) being symmetrical with respect to a plane of symmetry (S). The joint seal (3), starting from the plane of symmetry (S), comprises two limbs (3d) that extend at both sides in the peripheral direction (N), the two limbs (3d) extending over a total angular range of 20° to 180° and having a radially outwardly directed, arcuate limb outer face (3g). The joint seal (3), starting from the plane of symmetry (S), comprises a contact part (3b) that extends at both sides in the peripheral direction (N) and projects beyond the limbs (3d) in the axial direction (H), said contact part (3b) extending only across a partial angle of the two limbs (3d) in the peripheral direction (N). The contact part (3b) has a radially outwardly directed contact surface (3c) which is set back with respect to the limb outer face (3g) in the radial direction such that the limbs (3d) form a stop (3h) along the contact surface (3c), which stop is aligned in the axial direction (H). The sealing ring (2) and the joint seal (3) are adapted to each other such that, when assembled, the joint seal (3) rests laterally against the sealing ring (2) via the stop (3h) and that the contact surface (3c) of the contact part (3b) runs along the gap (2a) and covers same in the peripheral direction (N).