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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
"ECD-V4 System"ECD (Electronically Controlled Diesel): An electronically controlled system for diesel fuel injection.Final SessionFinal Session9SERVICE TECH Vol.472 04-6 Direct injection engines require high fuel injection pressure. In response, the ECD-V4 is a high-pressure injectionpump with improved features such as fuel pumping and distribution.(Compared with 60MPa for the ECD-V3, the ECD-V4 has an injection pressure of 130MPa) The final session of “Fundamentals of the ECD System” will explain the ECD-V4 injection pump, concentrating onthe differences to the ECD-V3. An inner cam type pumping mechanism is used in the ECD-V4 to obtain the injection pressure required for a directinjection engine (approx. 130MPa). The ECD-V3 injection pump uses a face cam type pumping mechanism.However, in this type the cam surface and roller “slip” at high pressure, resulting in mechanical loss. In the inner camtype this loss is minimized, so high pressure can be generated.11ECD-V4 OutlineEngine Speed SensorPulsarFeed PumpRollerPlungerCam Ring (Inner Cam)Timer PistonTiming Control Valve (TCV)RotorROMSolenoid Spill Valve (SPV)22Inner Cam MechanismInner CamCam RingRollerPlungerInner Cam Type Face Cam TypeFace Cam 10SERVICE TECH Vol.472 04-6 As the engine drives the injection pump drive shaft, the built-in feed pump is also rotated. Fuel is suctioned fromthe fuel tank and sent to the pump feed gallery. At this time the solenoid spill valve is open (SPV: OFF), and thefuel pump area (rotor) is replenished with fuel. The solenoid spill valve is closed (SPV: ON), and the inner cam and plunger pressurize the fuel trapped in therotor as the drive shaft rotates. At the instant when the pressure required to open the delivery valve is reached,fuel is pumped from the high-pressure pipes to the nozzle, and injection begins. The solenoid spill valve opens (SPV: OFF), and as pressure in the rotor reduces, the delivery valve closes andinjection ends.33Fuel Suction and PumpingSuctionPumping / InjectionEnd of InjectionSuction Pumping / InjectionSolenoid Spill Valve (SPV)During SuctionDuring SpillCamRollerPlungerCamRotorDuring SuctionDuring PumpingRotor RotationRollerCam RingRotorPlungerIn the inner cam, the roller and rotor rotate the inner side of the cam ring, which moves the plunger. 11SERVICE TECH Vol.472 04-6 This solenoid spill valve instantly applies high voltage (approx. 150V) to ensure fast responsiveness. It is installed inthe fuel passage connecting the fuel pump rotor to the pump chamber. Upon receiving a signal from the engine ECUfor fuel suction or the end of injection, the solenoid spill valve opens the passage to the fuel pump area (rotor). The solenoid spill valve in high injection pressure type injection pumps must switch OFF and ON once or twice instantlyduring the period from the start to the end of fuel injection. For this reason, it must have be highly responsive. An EDU(Electronic Driving Unit) is used for high-speed operation of the solenoid spill valve under high-pressure fuel conditions. Highvoltage is applied at the instant of actuation, attracting the valve with strong magnetism to close it quickly and completely. Upon receiving an “IJT signal” from the engine ECU, the EDU instantly applies high voltage (approx. 150V) from thehigh voltage generation circuit to the solenoid spill valve. This ensures fast valve response. The valve that wastemporarily attracted is held using “current control”, and it remains closed. At this time the solenoid spill valve currentis detected by the current detection circuit. If conditions are normal, an “IJF signal” is returned to the engine ECU. Ifconditions are abnormal, a malfunction is judged because the signal is not returned, and “IJT signal” output is halted.44Solenoid Spill Valve SPV (High Response Type)Pump ChamberOFF ONRotorPassage ClosedPassage OpenPump ChamberRotorEngine ECUEngine ECUON (Approx. 150V)4-1Actuation Method for the Solenoid Spill Valve (High Response Type)4-2 Operation of the EDU5V0V5V0VCurrentDetectionCircuitControl CircuitHigh VoltageGeneration CircuitEDUIJT SignalIJF SignalEngine ECUSPVDSPVFIJTIJFSPV0VApprox.150VSPVE2Solenoid Spill ValveSPVSolenoid Spill Valve Waveform 12SERVICE TECH Vol.472 04-6 The injection quantity control method is more or less the same as in the face cam type injection pump (ECD-V3). One difference is that fuel is sucked into the pressure chamber, and the solenoid spill valve stays open (OFF) andcloses immediately before the start of pumping. In other words, both the start of injection and end of injection can becontrolled. As for the ECD-V3, the ON and OFF timing of the solenoid spill valve are determined based on the signal from theengine speed sensor. The number of pulses and intervals between the pulses are detected, enabling the calculationof the cam angle of the inner cam.• This concludes the “Fundamentals of the ECD System” sessions. An explanation of the common rail system(CRS) will start in the next issue.55Method for Injection Quantity ControlCam Ring (Lift)(Injection Angle)Solenoid Spill Valve SignalShort ON Duration (Small Injection Quantity)(Injection Angle)Cam Ring (Lift)Solenoid Spill Valve SignalShort ON Duration (Large Injection Quantity)Solenoid Spill Valve (SPV)RotorEngine Speed SensorCam RingPulsarRollerDrive ShaftPulsarEngine Speed Sensor . System” will explain the ECD-V4 injection pump, concentrating onthe differences to the ECD-V3 . An inner cam type pumping mechanism is used in the ECD-V4 to obtain. injection pressure required for a directinjection engine (approx. 130MPa). The ECD-V3 injection pump uses a face cam type pumping mechanism.However, in this type