Multi-part Piston Ring Radial Pressure Distribution
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Solution Overview
Problem
Existing piston rings experience non-uniform radial pressure distribution, particularly under temperature effects, leading to poor oil scraping and cylinder wall striations due to uneven material distribution and lack of adaptability in spring support design.
Innovation Solution
A multi-part piston ring design featuring a spring support with a groove for a spring element, where the wall thickness is reduced in specific quadrants to create pockets, allowing for a modified radial depth and ovality, enabling uniform radial pressure distribution by adjusting spring position and area moment of inertia through a cosine function-based change in wall thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the piston ring is made as a single-part compression ring with uniform wall thickness, then the manufacturing is simple, but the radial pressure distribution becomes non-uniform under temperature effects
Solution Approach 1:
The spring support is designed with locally varying wall thickness, creating pockets with reduced material in specific circumferential regions. This non-uniform thickness distribution allows different sections of the piston ring to have different area moments of inertia, enabling compensation for temperature-induced deformation and achieving more uniform radial pressure distribution across the cylinder circumference.
Solution Approach 2:
The area moment of inertia of the spring support is deliberately varied as a parameter along the circumference by changing the wall thickness. This parameter change allows the structural stiffness to be adjusted locally, compensating for the non-uniform thermal expansion that occurs during engine operation and maintaining consistent contact pressure with the cylinder wall.
2Manufacturing precision
If the wall thickness is reduced locally to create pockets, then the radial pressure distribution improves, but the structural strength may be compromised
Solution Approach 1:
The wall thickness reduction is applied locally only in specific circumferential regions where pockets are needed for pressure distribution, while other regions maintain full thickness to provide structural strength. This selective thinning allows the ring to have both weak regions for pressure equalization and strong regions for structural integrity.
Solution Approach 2:
The spring support is effectively segmented into regions of different thickness - thicker regions for structural support and thinner pocket regions for pressure distribution. This segmentation allows the structure to optimize both strength and pressure uniformity by having different sections serve different functions.
3Reliability
If the spring element position is adjusted to improve pressure distribution, then the oil scraping performance improves, but the device complexity increases
Solution Approach 1:
The groove cross-section is varied locally in specific regions rather than uniformly throughout. This localized geometric variation allows precise control of spring element positioning and contact pressure in critical areas while keeping other regions simple, balancing performance improvement with manufacturing complexity.
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 achieves a consistent radial pressure distribution with minimal pressure at joint ends and maximum pressure elsewhere, preventing jumps in pressure and improving oil scraping performance and reducing temperature-induced issues.
Implementation Method 1
an at least single-part spring support (2) which is provided with a piston ring joint region (4) and an at least single-part spring element (3), which is positioned in a groove (9) provided in the region of the inner circumferential face of the spring support (2)
Implementation Method 2
the radial depth of the circumferential groove, in the circumferential direction of the spring support, is modified by a cross-sectional change in the radial wall thickness relative to the running surface of the spring support in such a manner that the annular spring element is positioned inside the groove with a predefined ovality in a plane perpendicular to the axial direction of the piston ring
Data Source
AI summary
A multi-part piston ring, containing an at least single-part spring support which is provided with a piston ring joint region and an at least single-part spring element, which is positioned in a groove provided in the region of the inner circumferential face of the spring support, wherein the wall thickness of the spring support is essentially equal in the region of the ends of the spring support facing the piston ring joint and in the rear region of the spring support, and a pocket which extends over a circumferential range of at least 60° and is created by local reduction of the wall thickness of the spring support is provided in each case between the rear region and the piston ring joint ends.