SUMMARY
The object of research is an electronic microprocessor control system for gas internal combustion engines with spark ignition for operation on liquefied petroleum gas. The system consists of two main subsystems, the accumulative power supply common rail LPG injection subsystem and the contactless electronic ignition subsystem with a movable voltage distributor. In addition, the control system also includes a subsystem for controlling the filling of the cylinders with the charge of the working mixture, consisting of a throttle valve and an idle speed regulator with a conical damper. The control system, depending on the software version, is capable of providing group or sequential injection of liquefied petroleum gas into the inlet pipe of each cylinder in the area close to the inlet valve. Such a control system can be used when converting (re-equipping) both new diesel engines into spark-ignition gas engines, and those that are in operation. The feasibility of such a conversion is to reduce operating costs with powerful vehicles for diesel fuel, by replacing it with cheaper and environmentally friendly liquefied petroleum gas.To test the efficiency of the control system, a D-240-LPG-«B» model gas engine was developed and manufactured to operate on liquefied petroleum gas. The gas engine was converted on the basis of the D-240 transport diesel engine (atmospheric, four-stroke, liquid-cooled, 4-cylinder engine with a piston diameter of 110 mm and a stroke of 125 mm). Reducing the compression ratio of the diesel engine was achieved by modifying a semi-closed diesel combustion chamber of the TsNIDI type into an open combustion chamber in the form of an axisymmetric «truncated cone». For efficient control of three subsystems of the D-240-LPG-«B» model gas engine, an electronic microprocessor control unit of the Avenir Gaz 37 «B» model was developed and manufactured. The tests carried out on the D-240-LPG-«B» gas engine with the Avenir Gaz 37 «B» control unit showed the efficiency of using the electronic microprocessor control system.