Empiric dependences of losses on a friction in classic and free-piston engines
Journal Title: Вісник Тернопільського національного технічного університету - Year 2015, Vol 80, Issue 4
Abstract
The results of friction and gas exchange losses investigation in two four-stroke gasoline internal combustion engines (ICE) – classic and free-piston ones are presented. The analysis of friction and gas exchange losses investigation in classic and free-piston ones was carried out. It was found that the magnitude of mechanical losses in the internal combustion engine depends on the mode of operation for nominal mode is 20 – 30% of the energy introduced with fuel. It is shown that fuel efficiency of internal combustion engine depends on many structural and operational factors, that's why while the design engine process for the specific purposes it is desirable to take into account the impact of parameters on performance. One of these factors is the level of mechanical losses of the ICE. The structure of friction elements according to ones types in classical and free-piston engines is shown. The data of experimental research of studied engines is presented. An empirical dependence components mechanical losses on the speed and load operating modes of the engine at different degrees of compression, different gap between the piston and cylinder etc were proposed. The empirical formulas were derived on the basis of experiments for obtaining the estimations of mechanical losses components contributions to the engine performance in general. The obtained empirical dependences can be used as a first approximation for gasoline internal combustion engines both classic and alternative engines of similar design. The comparative tests show that ceteris paribus the total losses due to friction in the free-piston engine are 25 – 35% less than in classic one. Friction losses of Crank-rocker mechanism are 30 – 40 % greater being compared to the classic ICE losses. It is shown that the feature of free-piston engine is that it has less friction loss in pairs: «piston – cylinder» and «piston – piston ring – cylinder» due to lack of alternating-sign radial forces that cause dynamic loads of piston and rings on the cylinder wall.
Authors and Affiliations
Tatyana Kolesnikova
Keywords
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