Bơm ECD-V - P - ECD-V4 Outline

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 Session

Direct injection engines require high fuel injection pressure In response, the ECD-V4 is a high-pressure injection

pump 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 on

the 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 direct

injection 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 cam

type this loss is minimized, so high pressure can be generated

1 ECD-V4 Outline

Engine Speed Sensor

Pulsar

Feed Pump

Roller

Plunger Cam Ring (Inner Cam) Timer Piston

Timing Control Valve (TCV)

Rotor ROM Solenoid Spill Valve (SPV)

Inner Cam

Cam Ring

Roller

Plunger

Face Cam

As the engine drives the injection pump drive shaft, the built-in feed pump is also rotated Fuel is suctioned from the fuel tank and sent to the pump feed gallery At this time the solenoid spill valve is open (SPV: OFF), and the fuel 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 the rotor 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 and injection ends

3 Fuel Suction and Pumping

Suction

Pumping / Injection

End of Injection

Solenoid Spill Valve (SPV)

During Suction

During Spill Cam

Roller

Plunger

Cam

Rotor

Cam Ring

Rotor

Plunger

In the inner cam, the roller and rotor rotate the inner side of the cam ring, which moves the plunger

This solenoid spill valve instantly applies high voltage (approx 150V) to ensure fast responsiveness It is installed in the fuel passage connecting the fuel pump rotor to the pump chamber Upon receiving a signal from the engine ECU for 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 instantly during 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 High voltage 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 the high voltage generation circuit to the solenoid spill valve This ensures fast valve response The valve that was temporarily attracted is held using “current control”, and it remains closed At this time the solenoid spill valve current

is detected by the current detection circuit If conditions are normal, an “IJF signal” is returned to the engine ECU If conditions are abnormal, a malfunction is judged because the signal is not returned, and “IJT signal” output is halted

4 Solenoid Spill Valve SPV (High Response Type)

Pump Chamber

Rotor

Passage Closed Passage Open

Pump Chamber Rotor

Engine

ON (Approx 150V)

4-1 Actuation Method for the Solenoid Spill Valve (High Response Type)

4-2 Operation of the EDU

5V

0V

5V

0V

Current Detection Circuit

Control Circuit

High Voltage Generation Circuit

EDU

IJT Signal

IJF Signal

Engine

ECU

SPVD

SPVF

IJT

IJF

SPV

0V

Approx 150V

SPV

E 2

Solenoid Spill Valve SPV

Solenoid Spill Valve Waveform

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) and closes immediately before the start of pumping In other words, both the start of injection and end of injection can be controlled

As for the ECD-V3, the ON and OFF timing of the solenoid spill valve are determined based on the signal from the engine speed sensor The number of pulses and intervals between the pulses are detected, enabling the calculation

of 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

5 Method for Injection Quantity Control

Cam Ring (Lift)

(Injection Angle)

Solenoid Spill Valve Signal

Short ON Duration (Small Injection Quantity)

(Injection Angle)

Cam Ring (Lift)

Solenoid Spill Valve Signal

Short ON Duration (Large Injection Quantity)

Solenoid Spill Valve (SPV)

Rotor

Engine Speed Sensor

Cam Ring Pulsar

Roller Drive Shaft

Pulsar

Engine Speed Sensor