Variable-Relief Piston Ring for Even Radial Pressure Distribution
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Solution Overview
Problem
The existing piston ring designs fail to evenly distribute radial pressures, leading to increased friction, wear, and damage due to uneven oil film thickness and pressure distribution around the ring end gap.
Innovation Solution
A piston ring design featuring a pressure relief chamfer on the outer side, with a varying axial dimension of the contact surface in the circumferential direction, which compensates for the uneven radial pressures by adjusting the gas contact surface height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If ground bevels are attached evenly over the entire circumference, then gas pressure contact surface is created to counteract gas pressure at the ring inner diameter, but radial pressures remain unevenly distributed leading to reduced oil film thickness at the ring end gap
Solution Approach 1:
The patent applies local quality by making the contact surface height variable in the circumferential direction. The contact surface height is reduced specifically in the region of the ring end gap (by 10-30% compared to other regions) to locally adjust the radial pressure distribution. This localized modification allows the contact surface to compensate for the uneven radial pressures without requiring complete circumferential modification, thereby maintaining oil film thickness at the ring end gap while still creating sufficient gas pressure counteraction force in other regions.
2Ease of manufacture
If contact surface height is uniformly distributed, then manufacturing is simplified, but circumferential variability of radial pressures cannot be compensated
Solution Approach 1:
The patent applies dynamics by introducing circumferential variability into the contact surface height. Instead of a static, uniform contact surface, the height is dynamically adjusted around the circumference, with specific regions (particularly near the ring end gap) having reduced height. This dynamic variation allows the contact surface to adapt to the circumferentially varying radial pressures, compensating for pressure concentration at the ring end gap while maintaining manufacturability through controlled height variations rather than complex three-dimensional shaping.
3Force
If contact surface area is increased to improve gas pressure counteraction, then friction and wear increase due to reduced oil film thickness, but reducing contact surface area diminishes gas pressure compensation
Solution Approach 1:
The patent applies parameter changes by modifying the contact surface height parameter in the circumferential direction. The contact surface height is reduced by 10-30% in the region of the ring end gap compared to other regions, creating a non-uniform height distribution. This parameter variation allows the contact surface to provide sufficient gas pressure counteraction in regions where full height is maintained, while reducing radial pressure concentration at the ring end gap to prevent excessive friction and wear, thus optimizing the balance between force generation and harmful factor reduction.
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
This design effectively counteracts the gas pressure at the ring inner diameter, reducing friction and wear by systematically varying the contact surface dimension to match the circumferential variability of radial pressures.
Implementation Method 1
Radial pressures of piston rings, which act between the running surfaces of cylinder and ring and which are intensified by the combustion pressure
Implementation Method 2
Due to the heat expansion differences between ring inner surface and ring outer surface, radial pressures are higher at the ring end gap
Data Source
AI summary
A piston ring includes a ring outer side, an upper ring flank and a lower ring flank, whereby the ring outer side has a pressure relief chamfer at an upper edge, so that only a lower part of the ring outer side forms a contact surface. An axial dimension of the contact surface varies in the circumferential direction.