Oil Scraper Ring Gap Layout for Piston Ring Stability
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Solution Overview
Problem
Existing oil scraper rings with constant small ring gaps suffer from instability due to high gas pressure, leading to increased oil entry into the combustion chamber and reduced stability of the second piston ring, particularly during operating states with negative pressure in the combustion chamber.
Innovation Solution
The oil scraper ring features a non-uniform ring gap design with larger gaps at the upper edge and recesses to facilitate gas flow, guiding blow-by gases into the intermediate space between scraper bars and through radial openings, reducing oil entry into the combustion chamber and enhancing the stability of the second piston ring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a small constant ring gap is used to maximize oil scraping effect, then oil scraping performance is improved, but gas pressure builds up causing instability of the second piston ring
Solution Approach 1:
The ring gap is designed with non-uniform width where the width varies in the circumferential direction. Specifically, the ring gap is narrower at certain regions to enhance oil scraping while wider at other regions to reduce gas pressure buildup, thereby simultaneously achieving both oil scraping effectiveness and ring stability
Solution Approach 2:
The ring gap width parameter is changed from a constant value to a variable value that changes along the circumferential direction. This parameter variation allows optimization of both oil scraping performance and gas pressure management by having different gap widths in different regions
2Reliability
If a small ring gap is used to prevent oil entry into combustion chamber, then oil control is improved, but gas pressure difference increases reducing ring stability during negative pressure operation
Solution Approach 1:
The ring gap is designed with non-uniform width where the width varies in the circumferential direction. Specifically, the ring gap is narrower at certain regions to enhance oil scraping while wider at other regions to reduce gas pressure buildup, thereby simultaneously achieving both oil scraping effectiveness and ring stability
Solution Approach 2:
The ring gap width parameter is changed from a constant value to a variable value that changes along the circumferential direction. This parameter variation allows optimization of both oil scraping performance and gas pressure management by having different gap widths in different regions
3Stability of the object's composition
If a larger ring gap is used to reduce gas pressure buildup, then ring stability is improved, but oil scraping effect is reduced
Solution Approach 1:
The ring gap is designed with non-uniform width where the width varies in the circumferential direction. Specifically, the ring gap is narrower at certain regions to enhance oil scraping while wider at other regions to reduce gas pressure buildup, thereby simultaneously achieving both oil scraping effectiveness and ring stability
Solution Approach 2:
The ring gap width parameter is changed from a constant value to a variable value that changes along the circumferential direction. This parameter variation allows optimization of both oil scraping performance and gas pressure management by having different gap widths in different regions
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 reduces oil combustion and particle emissions, particularly during overrun operation, by effectively managing gas pressure and guiding blow-by gases away from the combustion chamber, thereby improving the stability and performance of the second piston ring.
Implementation Method 1
The oil scraper ring having a non-uniform ring gap is also set up to guide a portion of the blow-by into the intermediate space between the two scraper bars of the piston ring so that a portion of the blow-by can flow through radial openings in the oil scraper ring inwards into the ring groove base from where it is guided through oil drain channels or the underlying axial play into the crankcase.
Implementation Method 2
The blow-by flow in particular enables oil droplets to be entrained from the gap between the two oil scraper bars and supplied to the crankcase.
Data Source
AI summary
An oil scraper ring (4) includes a ring element (6), having an upper ring edge (8), a lower ring edge, a ring inner side and a ring outer side (14. The ring element (6) is provided with two opposing contact surfaces (20), between which there is a ring gap (18. The ring element (6) is provided with at least one scraper bar (24, 26) on the ring outer side (14. The oil scraper ring (4) is provided with two recesses (28), each arranged on each contact surface (20), and each adjoining at least on the ring outer side (14), the respective contact surface (20) and the upper ring edge (8).