Tất cả tài liệu về bơm ECD-V (tài liệu đào tạo của Denso ECD): -Composition and Construction of ECD-V3 Pump System -Determining the Injection Timing -ECD-V Series -ECD-V4 Outline -ntake Restriction Control -Outline of Injection Ti
9SERVICE TECH Vol.468 03-10 The engine ECU judges the engine conditions and driving status of the vehicle based on the information receivedfrom the sensors. This is used to calculate the optimum fuel injection volume for the engine. The ECU then sends asignal to the solenoid spill valve of the injection pump to control the injection volume. Fuel injection starts the moment the cam plate forces the plunger to begin lifting. In other words, the timing of thestart of injection is determined by the position of the cam plate. Fuel is increased or decreased by controlling the timingof the end of injection. The end of injection is the moment when the solenoid spill valve is opened and high pressurefuel is spilt into the pump chamber.11Outline of Injection Volume Control22Control of Fuel Injection Volume2-1 Controlling the Injection VolumeEnd of InjectionCam PlateSolenoidSpill ValveBegins to Lift(Start of Injection)ONOFFCam LiftPlunger 10SERVICE TECH Vol.468 03-10 The engine ECU counts the pulses outputted from the speed sensor. The ECU opens (OFF) the solenoid spillvalve at a position corresponding to the number of pulses (injection end position) calculated by the ECU. The pulsecount is based on the number of NE (Engine speed) pulses counted after the toothless section of the pulsar isdetected. If the opening time of the solenoid spill valve is delayed, the injection time is lengthened, and the injection volumeis increased.2-2 Increasing and Decreasing the Injection VolumeToothless SectionEngine Speed Sensor Signal(Cam Angle)Injection Angle (Time)End of InjectionLift StartClosedClosedOpenSolenoid Spill ValveCam LiftIncreasing the Fuel Injection VolumeInjection Increase VolumeEngine Speed Sensor Signal(Cam Angle)Injection Angle (Time)Cam LiftSolenoid Spill ValveClosedClosedOpen SERVICE TECH Vol.468 03-1011 The engine ECU calculates when to open the solenoid spill valve from the signal received from the engine speedsensor. The engine speed sensor generates a pulse when its position aligns with the tooth of the pulsar (gear)attached to the drive shaft. The pulsar and the cam plate are unified into one unit by the coupling, so if the positionof the pulsar is detected it is possible to determine the rotation angle (position) of the cam plate. The solenoid spill valve is directly linked to fuel injection volume control, so the responsiveness of the valvestrongly influences the injection volume. If the coil resistance is lowered to secure the operating current, theresponsiveness is faster. The solenoid spill valve is closed during fuel suction/injection, but the actuating signal isactually a rapidly repeating ON/OFF signal.PulsarDriveShaft2-3 Actuating the Solenoid Spill ValvesSolenoid Spill Valve Actuating SignalCounter Electromotive ForceEnd of InjectionCurrentControlSolenoid Spill ValveWaveformCurrentControl 12SERVICE TECH Vol.468 03-10 Based on the engine speed, accelerator opening position and the signals received from the sensors, the engineECU calculates the "basic injection volume" and the "maximum injection volume" for the current condition of theengine. From these two volumes, the ECU selects the optimum value appropriate to the driving conditions anddetermines the final injection volume. The "maximum injection volume" means the maximum volume of fuel thatcan be pumped into the intake air under the current engine conditions. Determined by the engine speed and accelerator position.When the speed is constant, increasing the acceleratoropening will increase the fuel injection volume. This is the maximum injection volume for the intake aircapacity at a certain engine speed, so that the fuel combustswithout issuing black smoke. The maximum injection volumescalculated from the engine speed are finally determined aftercorrection according to factors such as the intake air pressure,fuel temperature and intake air temperature.33Calculation of the Injection Volume3-1 Calculating the Injection VolumeSolenoid Spill ValveBasic Injection VolumeMaximum Injection VolumeSelects the Smallest Injection VolumeCorrectionCoolant Temperature SensorIntake Air Pressure SensorFuel Temperature SensorIntake Air Temperature SensorDecides Final Injection VolumeAccelerator PositionEngine SpeedCorrectionResistorBasic Injection VolumeMaximum Injection Volume . spill valve is opened and high pressurefuel is spilt into the pump chamber.1 1Outline of Injection Volume Control2 2Control of Fuel Injection Volume 2-1 Controlling. the optimum fuel injection volume for the engine. The ECU then sends asignal to the solenoid spill valve of the injection pump to control the injection volume.