How Does a Diesel Engine Work?

[LeWillow]

The working principle of a diesel engine is: 1. Process: Kinetic energy is generated by burning diesel in the cylinder, which drives the crank connecting rod mechanism connected to the piston to perform reciprocating circular motion around the crankshaft, thereby outputting power. 2. Four-stroke diesel engine: A four-stroke diesel engine consists of four strokes: intake, compression, power, and exhaust. During the intake stroke, the piston is driven by the crankshaft to move from the top dead center to the bottom dead center, while the intake valve opens and the exhaust valve closes. When the piston moves from the top dead center to the bottom dead center, the volume above the piston increases, the gas pressure in the cylinder decreases, creating a certain vacuum.

[MacRonan]

I've been driving diesel vehicles for many years, and their working principle feels quite special. Simply put, it relies on compression ignition. A diesel engine first draws in a large amount of air, then the piston compresses it fiercely in the cylinder, causing the temperature to skyrocket instantly to several thousand degrees. Next, the fuel injector sprays diesel into the cylinder, and the diesel ignites spontaneously upon contact with the extremely hot air—no need for spark plugs like in gasoline engines. The burned gases then push the piston to perform work, and finally, the exhaust is expelled. The whole process is like an automatic heat engine, delivering tremendous power, quick acceleration, and fuel efficiency, making it ideal for hauling cargo or long-distance driving. However, you need to pay attention to using higher-quality diesel to avoid clogging the fuel injectors. The engine noise is louder, but you get used to it, and it even feels quite exhilarating. The key is to regularly maintain and check the compression system to prevent air leaks.

[LeJanelle]

As a student who frequently studies automobiles, I observe that diesel engine operation primarily consists of four steps: intake, compression, combustion, and exhaust. Air enters the cylinder, gets compressed and heated, then diesel is injected under high pressure and ignites spontaneously, generating energy to push the piston and rotate the crankshaft, finally expelling the exhaust. The absence of spark plugs is its most distinctive feature, relying on compression ignition for higher efficiency, lower fuel consumption, and greater durability. This design gives diesel vehicles high torque, making hill climbing effortless, though they require more preheating during startup, especially in winter when diesel becomes viscous and ignition slows down. I believe diesel engines are more environmentally friendly because complete combustion reduces carbon emissions, but remember not to idle too long to avoid excessive carbon buildup.

[VanJuliana]

During repairs, I often work with diesel engines, where the core principle is compressing air to heat it up before injecting fuel for combustion. The high compression ratio superheats the air, causing diesel to ignite instantly upon contact, generating power. The key lies in ensuring the fuel injection system functions properly—issues like clogged injectors or faulty fuel pumps can prevent ignition. Wear in compression components such as piston rings also reduces efficiency. Daily driving requires using the correct diesel grade, cleaning the air intake filter, and avoiding cold-start difficulties. This mechanism is somewhat simpler than gasoline engines, with lower repair costs, but noticeably noisier and more vibratory. Regular maintenance can extend its lifespan.