Tackling Emissions from the Internal Combustion Engine: Advances in Piston/Bore Tribology

A special issue of Lubricants (ISSN 2075-4442).

Deadline for manuscript submissions: 20 December 2024 | Viewed by 3205

Special Issue Editors


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Guest Editor
Tribonex AB, Knivstagatan 12, 753 23 Uppsala, Sweden
Interests: lubricant formulations (engine oils, metalworking emulsions); solubility and lubricity issues; additives and surface chemistry
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
USP Departamento de Engenharia Mecânica (PME), Universidade de São Paulo, São Paulo, Brazil
Interests: tribology; wear testing; friction; surface engineering; automotive engineering; piston ring

Special Issue Information

Dear Colleagues,

Legislative combustion engine bans marked a major decline in the R&D interest in the internal combustion engine (ICE), and many major OEMs aim to go 100% electric by 2030-2040. At the same time, many experts admit that, due to many objective factors, vehicles powered by ICEs will remain in operation for decades to come. Development of alternative carbon-neutral fuels can bring about a renaissance in ICE development as the practical limitations of the electric-only approach are exposed.

With over 1 billion ICE-powered cars currently in use in the world, improving the fuel efficiency and curbing emissions of the current fleet is crucial. Moreover, many lessons learnt through ICE tribology optimization work lay a useful knowledge foundation for electrical powertrain optimization. One key lesson is that a complete system approach is required in order to balance multiple aspects of vehicle performance, durability, and economy.

Since a significant part of energy losses in ICEs come from friction, engine tribology has been an important research topic over the past two decades and a significant progress in improving the engine efficiency has been achieved. Improving the piston/bore tribology has been one of the chief contributors to this progress. Significant advances have been made in light-weight piston design, the use of low friction coatings for piston skirts and the ring pack, the use of advanced honing methods and spray-coatings for the cylinder bore, etc.

This Special Issue aims to cover the current advances in the piston/bore tribology with contributions from world-leading experts in the field.

Dr. Boris Zhmud
Dr. Eduardo Tomanik
Guest Editors

Manuscript Submission Information

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Keywords

  • internal combustion engine
  • piston/bore tribology
  • emissions
  • piston ring pack
  • cylinder bore honing
  • thermal spray coatings
  • low friction coatings
  • APS
  • PTWA
  • TWAS

Published Papers (3 papers)

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Research

25 pages, 12647 KiB  
Article
Impact of Mid-to-Low-Ash, Low-Viscosity Lubricants on Aftertreatment Systems after 210,000-Kilometer Real-World Road Endurance Trials
by Heng Shao, Hua Hu, Yitao Luo, Lun Hua, Jinchong Pan, Gezhengting Zhu, Yan Jiao, Jingfeng Yan and Guangyuan Wei
Lubricants 2024, 12(7), 240; https://doi.org/10.3390/lubricants12070240 - 3 Jul 2024
Viewed by 437
Abstract
Engine lubricants globally face the challenge of meeting the demands of new engine technologies while enhancing energy efficiency and reducing emissions. Lubricants must enhance their performance and sustainability, improve reliability in complex and harsh environments, and minimize environmental impact and health risks. This [...] Read more.
Engine lubricants globally face the challenge of meeting the demands of new engine technologies while enhancing energy efficiency and reducing emissions. Lubricants must enhance their performance and sustainability, improve reliability in complex and harsh environments, and minimize environmental impact and health risks. This study explores the influence of two different formulations of low viscosity lubricants, tested through actual road endurance trials, on a hybrid vehicle’s aftertreatment system performance and overall emission levels. The study includes 120,000 km of endurance testing in four different challenging environments in China, as well as 90,000 km of endurance testing in a typical urban and highway driving cycle in a large city. Results indicate that emissions from the test vehicles during the 120,000 km and 210,000 km durable Worldwide harmonized Light vehicle Test Cycles (WLTCs) meet China’s Stage 6 light-duty vehicle emission standards, with the 210,000 km Real Driving Emission test (RDE) results also conforming to these standards. Relative to fresh TWC, the light-off temperature increased by a mere 60 °C, and the oxygen storage capacity declined by around 19% following endurance testing. Additionally, the GPF exhibited satisfactory performance after 210,000 km of endurance testing, showing lower backpressure values compared to the fresh-coated samples, with no notable ash buildup observed in the substrate. Drawing on the outcomes of actual road endurance testing, this study illustrates that employing low-to-mid-ash-content, low-viscosity lubricants is both compatible and reliable for aftertreatment systems in present or advanced hybrid technologies. Premium lubricants facilitate vehicles in sustaining compliant and stable emission performance, even amid harsh environments and complex operating conditions. Furthermore, the tested lubricants effectively inhibit excessive aging of the aftertreatment system over prolonged mileage. Moreover, this study discusses the feasibility of rapid aging evaluation methods for aftertreatment systems based on engine test benches, juxtaposed with actual road endurance testing. These findings and conclusions offer crucial references and guidance for enhancing lubricant performance and sustainability. Subsequent studies can delve deeper into the correlation between lubricant performance and environmental impact, alongside optimization strategies for lubricants across various vehicle models and usage scenarios. Full article
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18 pages, 7684 KiB  
Article
Experimental Investigation of a Free-Form Honed Cylinder Liner for Heavy-Duty Engines
by Frederik Stelljes, Florian Pohlmann-Tasche and Friedrich Dinkelacker
Lubricants 2024, 12(4), 132; https://doi.org/10.3390/lubricants12040132 - 16 Apr 2024
Viewed by 783
Abstract
For future internal combustion engines, driven by regenerative fuels, efficiency is more important than ever. One approach to reduce the losses inside the piston cylinder unit (PCU) is to improve the alignment of the liner and the piston. Therefore, a cylinder liner with [...] Read more.
For future internal combustion engines, driven by regenerative fuels, efficiency is more important than ever. One approach to reduce the losses inside the piston cylinder unit (PCU) is to improve the alignment of the liner and the piston. Therefore, a cylinder liner with a free form was developed at the Institute of Technical Combustion (ITV) of the Leibniz University Hannover which compensates radial and linear deformations along the stroke. The layout is based on a FEM simulation. The liner was manufactured by the Institute of Production Engineering and Machine Tools (IFW) of Leibniz University of Hannover with a novel turn-milling process. The liner was investigated on the heavy-duty Floating-Liner engine of ITV with a displacement of 1991 ccm and a bore diameter of 130 mm. The experimental results show improvement in the friction losses over the whole engine map in the range of 9% and up to 17.3% compared to a serial liner. Sealing efficiency could be improved up to 28.8%, depending on the operational point. Overall, the investigation aims for lower fuel consumption which would in result fewer emissions. Full article
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18 pages, 13365 KiB  
Article
Sources and Destinations of Oil Leakage through TPOCR Based on 2D-LIF Observation and Modeling Analysis
by Mo Li and Tian Tian
Lubricants 2023, 11(12), 522; https://doi.org/10.3390/lubricants11120522 - 9 Dec 2023
Viewed by 1502
Abstract
The Three-Piece Oil Control Ring (TPOCR) is becoming a viable option for heavy duty gas and hydrogen engines due to the low particle concentration in these engines. Although direct oil leakage from the gap is not likely to happen with the misalignment of [...] Read more.
The Three-Piece Oil Control Ring (TPOCR) is becoming a viable option for heavy duty gas and hydrogen engines due to the low particle concentration in these engines. Although direct oil leakage from the gap is not likely to happen with the misalignment of the upper and lower rail gaps, there exist other less-apparent oil leaking mechanisms through the TPOCR. This work is targeted at understanding the oil leakage’s source and destination through the rail and liner interfaces across the whole cycle. The 2D Laser Induced Fluorescence technique was applied on an optical engine to study the oil transport behavior. Combined with a TPOCR model for dynamics and lubrication, the mechanisms that cause rail twist and oil scraping by the upper rail were analyzed. It was found that the symmetrical rail can scrape the oil up in the up-strokes. The scraped oil first accumulates in the clearance between the upper rail and groove, as well as at the upper corner of the rail Outer Diameter before being transferred to both the third land and liner when the piston changes direction at Top Dead Center. Rails with an asymmetrical profile can reduce or enhance these effects depending the orientation of the rails. This study provides findings that could help design the engine to better control Lubricate Oil Consumption and properly lubricate the Top Dead Center’s dry region at the same time. Full article
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