Principle of diesel engine working process of diesel engine in fact like gasoline engine, each work cycle also experience intake, compression, power, and exhaust four stroke. But as a result of diesel engine fuel is diesel, and its viscosity is bigger than gasoline, not easy evaporation, while the combustion temperature was lower than those of gasoline, the mixture formation and therefore are different from gasoline engine ignition way.
Diesel engine is pure air suction in the intake stroke. , at the end of the compression stroke is close to diesel fuel by the fuel injection pump to increase the oil pressure to more than 10 mpa, spray through the injector into the cylinder, in a short time and high temperature compressed air mixing, form a combustible mixture. Due to their high diesel engine's compression ratio (usually for 16-22), so by the end of the compressed air in cylinder pressure can reach 3.5 4.5 MPa, and temperatures as high as 750-1000 k (and gasoline engine at this time of the mixture pressure will be 0.6 1.2 MPa, the temperature of 600-700 k), considerably more than diesel combustion temperature. After injection into the cylinder, so the diesel fuel in a short time immediately after mixed with air ignition burning themselves. Within the cylinder pressure increased to 6-9 mpa, temperature is up to 2000-2500 k. In high pressure gas, driven by piston movement and the crankshaft rotates downward and work, exhaust through the exhaust pipe same discharged into the atmosphere.
The ordinary diesel engine is driven by the engine camshaft, with the aid of high pressure oil pump room to each cylinder diesel fuel. This way of oil supply to changes over the engine speed, can't do the best oil under various rotational speed. Now more and more widely used electronically controlled common rail injection system of diesel engines can be better solved the problem. Common rail injection system consists of high pressure oil pump, oil public for tubing, fuel injector, electronic control unit (ECU) and some of the pipeline pressure sensors, the system of each injector through their high pressure pipe connected to the public for tubing, public for tubing injector hydraulic accumulator. Work, high pressure oil pump with high pressure fuel transfer to the public for tubing, high pressure oil pump, the pressure sensor and ECU closed-loop work, the oil pressure to achieve precise control of the public drainage tube, completely changed the phenomenon of oil supply pressure with engine speed changes. Its main characteristics are the following three aspects: 1, injection timing and completely separated from the fuel metering, injection pressure and injection process is controlled by ECU in due course. 2, can be adjusted according to engine working condition to each cylinder injection pressure, injection starting point, duration, and the pursuit of the best control point injection. 3, can achieve very high injection pressure, and can realize diesel injection. Than the gasoline engine, diesel engine with low fuel consumption (average 30% lower than that of gasoline engine), and diesel prices lower, so the better fuel economy; At the same time, the speed of the diesel engine generally lower than gasoline engine, torque than a gasoline engine is big, big, big noise at work, but the quality of the high cost of manufacturing and maintenance, also inferior to gasoline engine emissions. But with the development of modern technology, is to overcome these shortcomings are gradually of the engine, now is not the limousine have begun to use diesel engine.
