The engine is the power source of the automobile. Most of the automobile engine is thermal power plant, referred to as thermal machine.
A thermodynamic machine converts the heat generated by fuel combustion into mechanical energy by means of a state change in the working mass. Reciprocating piston four-stroke gasoline engine is the German Otto (Nicolaus A.otto) in the atmospheric pressure-type engine based on the invention and put into use in 1876.
Due to the use of air intake, compression, work and exhaust four strokes, the engine's thermal efficiency from the atmospheric pressure engine 11% to 14%, while the quality of the engine decreased by 70%. At present, automotive engines are internal combustion engines, the internal combustion engine is through the combustion of fuel, chemical energy into thermal energy, and then convert heat energy into mechanical energy of the thermal power machinery. The internal combustion engine is the thermal machinery with the highest thermal efficiency, but there is still a great potential to save energy and reduce the pollution of tail gas. For the volume regulation of the gasoline engine, in part of the load, the throttle opening due to the small engine pump gas loss, thus reducing the engine's mechanical efficiency, affecting the economy. Canceling the throttle is the most fundamental measure to improve the economy of gasoline machine. However, because the current gasoline engine is using throttle to adjust the mixture of gas, the elimination of throttle, the engine power output can not be controlled, so we must explore new ways. Gasoline direct injection technology is based on this idea. The throttle gate of the petrol engine is adjusted to the power output, and the power output is controlled by the fuel injection quantity. As a result, gasoline-fired gasoline engines can reduce fuel consumption by about 15% compared with current electronically controlled jet engines. However, with the direct injection technology, the existing three-way catalytic system is difficult to play a role, so that the emission quality of the engine decline, so we need to explore new ways. At present, the theory of homogeneous pressure ignition of mixed gas provides a good idea for solving this problem.