6E-366 Engine Control System (4HK1)
Along with the employment of a common rail type
electronic control fuel injection system, the fuel rail is
provided to store high pressure fuel between supply
pump and injectors. A pressure sensor and a pressure
limiter are installed on the fuel rail. The pressure sensor
detects the fuel pressure inside the fuel rail and sends
its signal to the engine control module (ECM). Based
on this signal, the ECM controls the fuel pressure
inside the fuel rail via the fuel rail pressure (FRP)
regulator of the supply pump. The pressure limiter
opens the valve mechanically to relieve the pressure
when the fuel pressure inside the fuel rail is excessive.
Flow Damper
Legend
1. Orifice
2. Slit
3. Piston
4. Return Spring
5. Housing
6. Fuel Rail
7. Injector
The flow dampers are installed at the outlet of fuel rail
to damp a pulsation of fuel pressure inside the fuel rail
or to cut off the fuel supply when the fuel leaks
downstream of flow damper. The fuel is supplied to the
injectors through an orifice of the piston. The pressure
pulsation occurring in the fuel rail is dampered by a
resistive force of the return spring and a passing
resistance of the orifice, wherein the piston acts as a
damper. Also, the leading end of piston closes the fuel
supply port to cut off the fuel supply, if the fuel leak
occurs in the injection pipe or injectors. Since fuel
pressure on the downstream side of flow damper
supplied through an orifice + resistive force of return
spring do not balance, the fuel pressure applied on the
piston surface prior to the orifice will allow the fuel to be
cut off. The piston will return when the fuel pressure
inside the fuel rail is less than 1.0 MPa (145 psi).
Fuel Rail Pressure Sensor
Refer to Engine Control Component Description.
Pressure Limiter
Legend
1. Valve
2. Valve Body
3. Valve Guide
4. Spring
5. Housing
6. Fuel Rail
7. Fuel Return Pipe
The pressure limiter relieves pressure by opening the
valve if abnormally high pressure is generated. The
valve opens when pressure in rail reaches
approximately 200 MPa (29,000 psi), and closes when
pressure falls to approximately 50 MPa (7,250 psi).
Fuel leakage through the pressure limiter re-turns to
the fuel tank.
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N6A6500E
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N6A6501E