Bơm ECD-V - P - Determining the Injection Timing

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

10SERVICE TECH Vol.470 04-2 The engine ECU determines the "Target Injection Timing" by using the signals received from the various sensors tocorrect the "Basic Target Injection Timing". This is calculated from the engine speed and accelerator position. The"Actual Injection Timing" is also calculated, based on the crankshaft angle standard position signal (TDC signal). Inorder to make the "Actual Injection Timing" match the "Target Injection Timing", the duty ratio of the timing controlvalve is calculated. Feedback control is performed to make the injection timing the same as the target value.• Calculating the Injection Timing Target injection timing formula• Basic Target Injection Timing The engine ECU calculates the engine load from theengine speed and accelerator position signals, anddetermines the "Basic Target Injection Timing". Thehigher the engine speed, or the larger the acceleratorposition, the longer the advance.Target Injection Timing=Basic Target Injection Timing +Intake Air Pressure Correction +Coolant Temperature Correction+Intake Air Temperature Correction11Determining the Injection Timing 11SERVICE TECH Vol.470 04-2 The engine ECU compares the "Target Injection Timing" and "Actual Injection Timing" that have been calculated. Itthen performs duty actuation on the timing control valve (TCV) in order to match the two timing values. As a result,the injection pump roller ring turns, and the injection timing changes.22Injection Timing Control MethodCrankshaftPosition SignalCrankshaftPosition SignalEngine SpeedSensor SignalTarget InjectionTimingActual Injection TimingSignal from Engine ECUEngine SpeedSensor SignalSignal from Engine ECU(Retard Condition)(Actuating the Advance Side)Actual InjectionTimingTarget InjectionTimingTransferRetardTiming Control Valve(Duty Ratio: Large)[Present Condition](Duty Ratio: Medium) [After Control]#0#0InjectionTiming ControlTiming Control ValveAdvance 12SERVICE TECH Vol.470 04-2 In addition to fuel injection volume and timing control, the ECD system performs other types of control to enable thecomfortable operation of the engine and the vehicle.• Idling Speed Control• EGR Control• Intake Restriction Control• Glow Control• Others33Various System ControlsMain System Controls3-1 Outline of System Controls 13SERVICE TECH Vol.470 04-2 This control function minimizes the variation in the idling speed caused by changes in the engine load. A"Target Speed" is calculated to meet the engine and driving conditions, which is used to control speed whenthe engine is idling. The engine ECU detects the "Refrigerant Temperature, Shift Position, Air Conditioner Operation" signals,and compares the calculated "Target Speed" with the engine speed (engine speed sensor signal) at thattime. If the engine speed is different, the fuel injection volume is adjusted, and feedback control isperformed in order to match it with the target idling speed.• Engine speed is lower than target speed - - - - - - - - - - - - - - - - - -Injection volume is increased• Engine speed is higher than target speed - - - - - - - - - - - - - - - - - -Injection volume is decreased The "Target Engine Speed" for each enginecondition has already been stored in the engine ECUmemory. When the ECU receives information aboutthe engine conditions from the sensors andswitches, it searches its memory and determinesthe appropriate target value.44Idling Speed Control (ISC)4-1 Control Outline4-2 Speed Control MethodDetection of Idling ConditionsIdling Speed Control4-3 Determining the Target Engine Speed . speed - - - - - - - - - - - - - - - - - -Injection volume is increased• Engine speed is higher than target speed - - - - - - - - - - - - - - - - - -Injection. accelerator position signals, anddetermines the "Basic Target Injection Timing& quot;. Thehigher the engine speed, or the larger the acceleratorposition, the