1. Intake Valve Opens: During the intake stroke of the engine, the intake valve opens, allowing a mixture of air and fuel to enter the cylinder.
2. Fuel Injector Opens: In modern engines, an electronically controlled fuel injector is mounted near the intake valve. When the engine control unit (ECU) determines that fuel needs to be injected, it sends a signal to open the fuel injector.
3. Fuel Sprayed: The fuel injector opens and sprays a fine mist of fuel directly into the intake port or into the cylinder, depending on the type of fuel injection system used.
4. Fuel Mixing with Air: The atomized fuel droplets mix with the incoming air to form a combustible mixture. This mixture of air and fuel is often referred to as the "air-fuel mixture" or simply "fuel mixture".
5. Intake Valve Closes: After the intake stroke, the intake valve closes, sealing the air-fuel mixture inside the cylinder.
6. Compression Stroke: The piston then moves up in the cylinder, compressing the air-fuel mixture, increasing its pressure and temperature.
7. Combustion: Just before the piston reaches its highest point (top dead center), the spark plug ignites the compressed air-fuel mixture, creating an explosion that drives the piston down in the cylinder.
This is the basic process of how fuel gets into the combustion chamber of an internal combustion engine through fuel injection. The exact design and mechanism may vary depending on the specific fuel injection system used, such as port fuel injection or direct fuel injection, which differ in the timing and location of fuel injection.
