2. Outline 2-1. Outline of System The common rail system was developed primarily to cope with exhaust gas regulations for diesel engines, and aimed for A. System Characteristics 1. further improved fuel economy; 2. noise reduction; and 3. high power output. ‡ The common rail system uses a type of accumulation chamber called a rail to store pressurized fuel, and injectors that contain electronically controlled solenoid valves to spray the pressurized fuel into the cylinders. ‡ Because the engine ECU controls the injection system (including the injection pressure, injection rate, and injection tim- ing), the injection system is unaffected by the engine speed or load.
‡ This ensures a stable injection pressure at all times, particularly in the low engine speed range, and dramatically decreas- es the amount of black smoke ordinarily emitted by a diesel engine during start-up and acceleration. ‡ As a result, exhaust gas emissions are cleaner and reduced, and higher power output is achieved. a. Injection Pressure Control ‡ Enables high-pressure injection even at low engine speeds. ‡ Optimizes control to minimize particulate matter and NOx emissions. b. Injection Timing Control Enables finely tuned optimized control in accordance with driving conditions. c. Injection Rate Control Pilot injection control sprays a small amount of fuel before the main injection.
'SQQSR6EMP7]WXIQ -RNIGXMSR8MQMRK'SRXVSP -RNIGXMSR6EXI'SRXVSP 3TXMQM^EXMSR 4MPSX-RNIGXMSR 7TIIH -RNIGXMSR6EXI 'SQQSR6EMP7]WXIQ 1EMR MRNIGXMSR -RNIGXMSR8MQMRK 'VEROWLEJX%RKPI -RNIGXMSR5YERXMX]'SRXVSP 'SRZIRXMSREP 4YQT ']PMRHIV-RNIGXMSR :SPYQI'SVVIGXMSR 7TIIH d. EGR (Exhaust Gas Recirculation) Control 5() By recirculating the exhaust gas into the intake side of the engine, the combustion temperature is reduced and NOx is decreased. -2- -RNIGXMSR4VIWWYVI'SRXVSP 3TXMQM^EXMSR, 'SQQSR6EMP7]WXIQ -RNIGXMSR4VIWWYVI 'SRZIRXMSREP 4YQT 7TIIH MKL4VIWWYVM^EXMSR 4EVXMGYPEXI 23\ -RNIGXMSR 4VIWWYVI