Diesel engines, as an efficient power device, are widely used in transportation, industry, agriculture and other fields. The following is a summary of the core knowledge for you from aspects such as basic principles, structural features, advantages and disadvantages, application scenarios and technological development:
Basic principle: The charm of compression ignition
The biggest difference between diesel engines and gasoline engines is the ignition method:
Diesel engines achieve ignition by "heating up compressed air" - the inhaled air is compressed by the piston (the compression ratio is usually 15-22:1, much higher than the 8-12:1 of gasoline engines), and its temperature rises to 700-900℃. At this point, the fuel injector injects high-pressure diesel into the cylinder, and the diesel spontaneously ignites upon encountering the high-temperature air, pushing the piston to do work. The gasoline engine is "ignited" : the mixture of oil and gas is ignited by the spark plug.
The core components of a diesel engine include:
Cylinder and piston: Complete the four-stroke cycle (intake → compression → power → exhaust).
High-pressure fuel pump + injector: Pressurizes diesel (modern common rail systems can reach over 2000bar), precisely controlling the timing and quantity of fuel injection.
Turbocharger: It uses exhaust energy to drive the turbine, compressing more air into the cylinders and enhancing power.
EGR (Exhaust Gas Recirculation) system: Reduces combustion temperature and decreases nitrogen oxide (NOx) emissions.