In the common rail type fuel injection system, the pressurized
fuel is supplied by the supply pump, stored in the common rail, and injected through the solenoid
type injectors. Construction Diagram The engine-ECU transmits signals to the solenoid valves in the injectors in order to control
the fuel injection timing and injection amount. In the common rail type fuel injection system, the pressurized fuel (approximately 180
MPa max.) supplied by the supply pump is stored in the common rail. Thus, the system ensures
a stable injection pressure at all times, even at low speeds, without being affected by engine
speed or load. The engine-ECU monitors the internal pressure of the common rail by way of the rail pressure
sensor, and actuates the suction control valve to deliver fuel, thus enabling the fuel in the
common rail to attain the target pressure. Furthermore, the system uses a limiter valve in the
common rail to prevent the fuel pressure in the common rail from rising excessively. The engine-ECU
sends signals to the solenoid type injectors, which use solenoid valves to open and close the
fuel passages. Because these solenoid type injectors can precisely control the fuel injection amount
and injection timing, they can suppress the generation of black smoke, which is unique to diesel engines. Furthermore, the system divides the injection of fuel in two stages, consisting of pilot
injection followed by main injection. This allows the combustion to start gently during main
injection, effectively reducing vibration and noise.
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