Introduction to Marine diesel engine parts and knowledge of diesel engines

The main difference in the basic knowledge of diesel engines is that they inject petroleum or diesel into the cylinder as fuel for combustion, rather than using a mixture of gasoline as fuel. At the same time, during the compression stroke, it is not the flammable mixture gas that is compressed, but only the air. Gasoline engines use spark plugs to ignite fuel, while diesel engines have a fuel injector at the top that uses high-temperature air to ignite diesel, hence the name compression ignition. It also has four strokes: The first stroke is the intake stroke, which only sucks air into the cylinder. The second stroke is compressed air. The gasoline engine only compresses the volume of the fuel mixture to 1/6 to 1/9 of that at the end of the intake stroke.

If more is compressed, in the middle of the compression process, the fuel mixture will burn due to the temperature rising above the flash point, and the machine will reverse and fail to work properly. Diesel engines can compress the volume of air to 1/6 to 1/22 of the end of the intake stroke, with a pressure reaching around 4 megapascals and a temperature as high as 500 to 700 degrees Celsius, exceeding the ignition point of diesel. The third stroke is the power stroke. At the end of the compression stroke, diesel is injected into the cylinder at high speed from the fuel injector under high pressure. The mist droplets come into contact with the hot air and burn immediately. Due to the long injection time of diesel, the combustion time is also long, and the combustion temperature can reach about 2000℃. The fourth stroke is the exhaust stroke, which is the same as that of a gasoline engine.