Researches of influence kind of piston on some parameters of the S12-U Wola diesel engine

Increased weight and greater requirements, regarding manoeuvring opportunities need extension of the power of combustion engines determining their powertrain units. In case of the family „W” engines, following developmental versions came into existence as a result of the modernization of the earlier version, among others thru the optimization of the combustion process, applying of the supercharging, as well as strengthening of the internal construction, which made it possible to carry greater thermal and mechanical loads. The subjects of the study were pistons made from composite materials of the small hysteresis of the alloy mounted on the S12-U combustion engine. In the novel construction of the piston, the outline of the overcoat was modified, the shape of the combustion chamber, the hole for the piston pin, grooves for the piston rings and shape of internal surfaces remained unchanged. A characteristic feature of the novel piston is the smaller hysteresis of the coefficient of thermal expansion composite alloy, (cid:3)(cid:68)(cid:15) of which the pistons were made, whereas a so-called hysteresis is the difference of the coefficient (cid:3)(cid:68) , which occurs during warming and piston cooling, and takes place during working of the piston in the combustion engine. The smaller hysteresis of the coefficient (cid:3)(cid:68) makes the decreasing clearances between piston and cylinder possible, what has a beneficial influence on work parameters of the combustion engine, especially under conditions of partial loading of the engine. Basic parameters of the engine for the maximum torque characteristics and load characteristics are the object of the paper.