In a diesel engine, what is the primary fuel metering method?

In a diesel engine, the primary fuel metering method is direct injection. This method involves injecting fuel directly into the combustion chamber of the cylinder, allowing for precise control of the fuel quantity and timing relative to the engine's compression cycle. This direct injection process enhances fuel efficiency, improves combustion, and helps reduce emissions by ensuring optimal mixing of air and fuel within the cylinder.

Direct injection is especially suitable for diesel engines because it effectively handles the higher combustion pressures and temperatures that characterize diesel operation. By atomizing the fuel directly into the compressed air, it creates a more effective and efficient combustion environment, leading to better performance and power output, along with improved fuel economy compared to other methods.

This distinguishes it from other fuel metering methods that may not be as efficient or applicable in a diesel engine context, such as carburetor mixing, which is primarily used in gasoline engines, or batch fuel delivery, which is less precise than the continuous flow allowed by direct injection systems.