2.2 Outline of System [1] Composition The common rail system consists primarily of a supply pump, rail, injectors, and engine ECU. Fuel Temperature Sensor Vehicle Speed Accelerator Opening Intake Air Pressure Intake Air Temperature Coolant Temperature Crankshaft Position Cylinder Recognition Sensor Engine ECU Intake Airflow Rate Rail Pressure Limiter Injector Rail Pressure Sensor Supply Pump Fuel Temperature Sensor SCV (Suction Control Valve) Fuel Tank Q000144E [2] Operation (1) Supply pump (HP3) a. The supply pump draws fuel from the fuel tank, and pumps the high pressure fuel to the rail. The quantity of fuel discharged from the supply pump controls the pressure in the rail.
The SCV (Suction Control Valve) in the supply pump effects this control in accordance with the command received from the ECU. (2) Rail a. The rail is mounted between the supply pump and the injector, and stores the high- pressure fuel. (3) Injector (G2 type) a. This injector replaces the conventional injection nozzle, and achieves optimal injection by effecting control in accordance with signals from the ECU. Signals from the ECU determine the length of time and the timing in which current is applied to the injector. This in turn, determines the quantity, rate and timing of the fuel that is injected from the injector. (4) Engine ECU a.
The engine ECU calculates data received from the sensors to comprehensively control the injection quantity, timing and pressure, as well as the EGR (exhaust gas recirculation). 4