What is it about?

The piston ring–cylinder liner (PRCL) conformation is a critical aspect for friction in internal combustion engine. On one hand, limited ability of the piston rings to conform to the bore shape will lead to oil consumption and corresponding emission of particulate and hydrocarbons. On the other hand, higher piston ring tension, which is required to achieve the oil consumption and exhaust emission requirements, leads to increased friction losses and ultimately results in increased fuel consumption and GHG emissions. If the liner would have a perfect round and cylindrical shape in the running engine state, the piston and piston rings could be better adapted, leading to less friction and oil consumption with reduced piston ring tension. This means that increasing the roundness of the deformed liner in the running engine offers a significant improvement potential.

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Why is it important?

The internal combustion engine is the main component of the majority of transportation and freight sectors worldwide. Even with the currently discussed development of electrical vehicles, the World Energy Outlook expects that the already existing large number of internal combustion engines in the transportation sector will still increase. Therefore, measures to reduce the greenhouse gas emission in this sector is vital for sustainable development, regarding also that cost-effective transportation is extremely important for national economies. This means that the increase in the efficiency of the internal combustion engine is an urgent need. A large potential for an increase in efficiency is seen with friction reduction, which is the target of this article.


Many expected the internal combustion engine will die soon. I believe that this old concept can utilize the advancement in technology to become more efficient and powerful. This includes utilizing cleaner fuels and increasing its efficiency through reducing the friction and enhancing the the injection and combustion characteristics. This paper is another step in that.

Ahmad Alshwawra
Institut für Technische Verbrennung

Read the Original

This page is a summary of: Increasing the roundness of deformed cylinder liner in internal combustion engines by using a non-circular liner profile, International Journal of Engine Research, December 2019, SAGE Publications, DOI: 10.1177/1468087419893897.
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