DESIGNING THE SHAPE OF THE COMBUSTION CHAMBERS FOR GAS ENGINES CONVERTED ON THE BASIS OF THE DIESEL ENGINES

This paper describes the advantages of using gas motor fuels by vehicles, in particular liquefied petroleum gas, co MPared to conventional diesel fuel. The expediency of converting the diesel-based vehicles to gas internal combustion engines with spark ignition has been substantiated. The ways to reduce the degree of compression of the diesel engines when they are converted into gas internal combustion engines with spark ignition have been analyzed. It has been shown it is expedient, in order to convert the diesel engines into gas internal combustion engines with spark ignition, to use the Otto thermodynamic cycle with a decrease in the geometric degree of compression. Techniques to increase the combustion chamber volume have been analyzed, as well as the expediency of applying each of them to reduce the compression degree of the diesel engines with different types of non-separated combustion chambers. An open combustion chamber has been substantiated and designed in the form of an inverted axisymmetric «truncated cone», which made it possible to reduce the geometric compression degree only by increasing the volume of the combustion chamber in the piston. The designed shape of the combustion chamber allows the use and refinement of standard diesel pistons instead of producing special new gas pistons. The gas internal combustion engine of model D-240-LPG has been designed and fabricated, in which the liquefied petroleum gas is fed to the inlet pipeline. The engine is equipped with a contactless electronic ignition system with a movable voltage distributor, as well as pistons with the newly designed shape of the combustion chamber. The engine has been converted based on the D-240 diesel engine. The bench testing of the model D-240-LPG diesel engine has confirmed the expediency of converting the diesel engines to gas internal combustion engines using the Otto cycle. The tests have shown that the energy and economic parameters of the gas engine with the proposed shape of a combustion chamber correspond to the parameters of modern internal combustion engines with spark ignition. The results obtained make it possible to optimize the technology of re-equipping the diesel engines with gas ICEs and thus reduce its cos