In a diesel engine, how is fuel delivered into the cylinders?

In a diesel engine, fuel is delivered directly into the combustion chamber of the cylinder through a process known as direct injection. This method allows for precise control of the fuel-to-air mixture and enhances the efficiency and performance of the engine. In direct injection systems, the fuel is injected at high pressure, allowing it to penetrate the compressed air in the cylinder, leading to better atomization and improved combustion.

The use of direct injection is crucial in diesel engines, as it contributes to their characteristic high torque and fuel efficiency. Additionally, this injection method helps in controlling emissions by optimizing the combustion process, leading to cleaner exhaust gases. The direct injection of fuel contrasts with other methods, such as indirect injection, where fuel is first mixed with air in a pre-combustion chamber before entering the main combustion chamber, which is less common in modern diesel engines.