B. Operation a. Supply pump (HP3/HP4) The supply pump draws fuel from the fuel tank, and pumps the high pressure fuel to the rail. The quantity of fuel dis- charged 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. b. Rail The rail is mounted between the supply pump and the injector, and stores the high pressure fuel. c. Injector (G2 type) ‡ 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. d. Engine ECU 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). 2-3. Fuel System and Control System A. Fuel System This system comprises the route through which diesel fuel flows from the fuel tank to the supply pump, via the rail, and is injected through the injector, as well as the route through which the fuel returns to the tank via the overflow pipe.
B. Control System In this system, the engine ECU controls the fuel injection system in accordance with the signals received from various sensors. The components of this system can be broadly divided into the following three types: (a.) Sensors; (b.) Engine a. Sensors ECU; and (c.) Actuators. Detect the engine and driving conditions, and convert them into electrical signals. b. Engine ECU Performs calculations based on the electrical signals received from the sensors, and sends them to the actuators in order c. Actuators to achieve optimal conditions. Operate in accordance with electrical signals received from the ECU.
Injection system control is undertaken by electron- ically controlling the actuators. The injection quantity and timing are determined by controlling the length of time and the timing in which the current is applied to the TWV (Two-Way Valve) in the injector. The injection pressure is determined by controlling the SCV (Suction Control Valve) in the supply pump. 7IRWSV %GXYEXSV ()273TVSHYGXW )+6MWTVSHYGIH F]SXLIVQERYJEGXYVIW 'VEROWLEJX4SWMXMSR7IRWSV2) )RKMRI7TIIH ']PMHIV6IGSKRMXMSR7IRWSV+ ']PMRHIV6IGSKRMXMSR -RNIGXSV y-RNIGXMSR5YERXMX]'SRXVSP c-RNIGXMSR8MQMRK'SRXVSP 0SEH )RKMRI )'9 %GGIPIVEXSV4SWMXMSR7IRWSV 6EMP4VIWWYVI7IRWSV c-RNIGXMSR4VIWWYVI'SRXVSP 7YTTP]4YQT7':
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