Efficiency of Application of Friction Modifiers in Internal Combustion Engines According to the Operational Tests Result

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ciency of Application of Friction Modifiers in Internal Combustion Engines According to the Operational Tests Results J. Padgurskasa, *, E. Jaškauskasa, R. Rukuižaa, I. Kavaliovab, **, and F. Grigorievb aVytautas Magnus University, Akademija, Kaunas district, LT-5336 Lithuania Bely Institute of Mechanics of Metal–Polymer Systems, National Academy of Sciences of Belarus, Gomel, 246050 Belarus *e-mail: [email protected] **e-mail: [email protected]

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Received April 14, 2020; revised July 5, 2020; accepted July 7, 2020

Abstract—The efficiency of using of mineral engine oil modifier to restore compression of the cylinder–piston group of internal combustion engines is investigated. According to the results of full-scale tests of four different automobiles operating in an urban environment, the effect of increasing the compression of the cylinders to 20%, compared with the original, and reducing the pressure difference between them up to four times, was determinated. The effect reached a stable value after a run of 2000–4000 km and remained until the end of the experiment (10000 km). It was found that when implementing the recommended procedure for flushing the engine before using oil with a friction modifier (FM), complete engine failure can occur. According to preliminary data the probability of this event is 20–30%. Keywords: internal combustion engines, cylinder–piston group, friction modifiers, engine oil, cylinder pressure, oil pressure, reliability DOI: 10.3103/S1068366620050141

INTRODUCTION The internal combustion engine (ICE) is one of the most loaded units of an automobile. It includes many friction units operating under high loads, sliding speeds, and temperatures. The cylinder–piston group (CPG), especially the piston rings and the cylinder liner are operating in the most extreme conditions. The most unfavorable conditions for their operation arise when the engine starts, when there is insufficient lubrication, as well as at low temperatures, when its viscosity is too high. The established engine operating mode is also quite heavy: the fuel mixture condenses on the cylinder walls, washing off the oil film, and high temperatures lead to degradation of the lubricant [1, 2]. In general, we can assume that a significant part of mechanical losses, as well as the level of harmful emissions in exhaust gases, depend on the wear of CPG parts. The traditional method of increasing the durability and reliability of the ICE CPG is to increase the hardness of the working surfaces of their parts by surface modification or by applying special coatings. It allows to reduce the elastoplastic deformations, abrasion, oxidation, and tribocorrosion. There are many known methods of surface hardening that contribute to increasing the reliability of the CPG and increasing the specific power of the ICE as a whole. However, this approach has its limitations. With an increase in the hardness of the working surfaces of the CPG, the contact area of the contacting parts decreases and, as a

result, the specific load increases, which u

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