Before explaining how this engine works you must understand the difference between petrol and diesel. Gasoline (if its quality) not combusted alone, need the help of a heat source (plug).The diesel on the other hand has the property of self combustion, namely, if injected when the fresh air is hot, expands.
One of the main features of this engine is that it enters the cylinder provided the maximum amount of air possible, whereas in a gasoline engine need a flow meter to know the exact amount of air entering the intake and well to inject the necessary proportion of gasoline. Power is provided by us with the accelerator pedal pumping more oil or less to the combustion chamber.
Cycle operation 1-Admission of fresh air compression 2-3-4-injection and combustion Escape
In the compression cycle, by the piston and the two valves are closed, PMS we compress the fresh air in. This compression causes temperature increase. At that very moment we inject diesel and pulverized combustion occurs and subsequent expansion.
There are two types of diesel. Indirect injection (current engines) where the oil is burned directly in the combustion chamber (very important the high injection pressure "rail cammon" to 1600 bar and indirect injection was less important where the fuel spray, pressure is injection, due to the existence of a high turbulence precombustion producing.
Advantages and disadvantages of diesel engine relative to the engine Otto.
-Increased thermal efficiency
-Lower consumption-Less polluting
-Longer life with less maintenance cost.
-Greater weight, rougher and noisier operation
-Most Expensive (higher manufacturing cost)
-More hard starting cold (only indirect injection engines where the glow plugs are necessary. In direct injection function is the antipollution).