MATERIAL CONSUMPTION CRITERIA OF PISTON – CON – ROD ELEMENTS SYSTEM OF COMBUSTION ENGINE

Abstract

The following article includes the analysis of mechanical and thermal load criteria of combustion engine. Those criteria have been divided into tribological, technical in detail and technical in general. The above criteria have been related to piston-con-rod system, in which, two tribological centres were specified. One centre included, piston-piston rings and cylinder, in which, piston rings serve as labyrinth seal and the cylinder constitutes piston guides. Crank bearings and main bearings of engine crankshaft constitute the second centre. From the point of tribological view, piston-piston rings and cylinder constitute slide and thrust bearing lubricated hydrodynamically, while crankshaft bearings a-c-t as slide and journal bearings also lubricated hydrodynamically. In the description of thermal load of the above-mentioned tribological centres, special attention was paid to criteria that ensure their motion reliability and durability of engine operation. Whereas in the description of mechanical load of elements constituting investigated centres, some criteria were determined resulting from their functionality and fatigue strength of the material they were made of. Criteria of thermal loads were based on mean density flux of heat conducted through the walls of engine elements, paying attention to their low precision of evaluation. It has been emphasized that synthetic criteria indicators are the most precise. They are determined on the basis of engine load measurements during its operation. Those criteria allow us to describe the operating process of con-rod-piston diesel engines and at the same time it is possible to expose their technical condition which is of essential practical meaning. The wear process of tribological centres that takes place during operating in piston-con-rod system, affects the course of engine working process and its techno-economic indicators.