Marine Diesel Engine Parts Introduction - Diesel Engine

The main difference in the basic knowledge of diesel engines is that it injects petroleum or diesel into the cylinder for combustion as fuel, rather than using a mixture of gasoline as fuel. At the same time, in the compression stroke, it does not compress the combustible mixture but simply compresses the air. The gasoline engine uses a spark plug to ignite the fuel, while the diesel engine has a fuel injector at the top, using hot air to ignite the diesel, so it is called compression ignition. It also has four strokes: The first stroke is the intake stroke, where only air is吸入缸内。 The second stroke is to compress the air， and the gasoline engine only compresses the volume of the fuel mixture to 1/6 to 1/9 at the end of the intake stroke.

If the compression is more, during the compression process, the fuel mixture will burn due to the temperature rising above the ignition point before the end of the intake stroke. The machine will reverse and cannot work normally. The diesel engine can compress the volume of the air to 1/6 to 1/22 at the end of the intake stroke， with a pressure of about 4 megapascals and a temperature of up to 500 to 700℃， which is higher than 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 under high pressure from the fuel injector， and the misty liquid droplets meet the hot air immediately and ignite. Due to the long injection time of diesel， the combustion time is also longer， with a combustion temperature of about 2000℃. The fourth stroke is the exhaust stroke， which is the same as the gasoline engine.