Land Rover Common Rail System Crs Denso Manual

Operation Section1–46
4. RAIL DESCCRIPTION
4.1 Rail Functions and Composition
zThe function of the rail is to distribute fuel pressurized by the supply pump to each cylinder injector.
zThe shape of the rail depends on the model and the component parts vary accordingly.
zThe component parts are the rail pressure sensor (Pc sensor), pressure limiter, and for some models a flow damper and
pressure discharge valve.
4.2 Component Part Construction and Operation
Component PartsFunctions
Rail Stores pressurized...

Operation Section1–47
(1) Pressure Limiter
• The pressure limiter opens to release the pressure if abnormally high pressure is generated. If pressure within the rail
becomes abnormally high, the pressure limiter operates (opens). It resumes operation (closes) after the pressure falls
to a certain level. Fuel released by the pressure limiter returns to the fuel tank.
< NOTE >
The operating pressures for the pressure limiter depend on the vehicle model and are approximately 140-230MPa for
the valve opening...

Operation Section1–48
(3) Flow Damper
• The flow damper reduces the pressure pulsations of the fuel in the pressurized pipe and supplies fuel to the injectors
at a stabilized pressure. The flow damper also presents abnormal discharge of fuel by shutting off the fuel passage
in the event of excess fuel discharge, for example due to fuel leaking from an injection pipe or injector. Some flow
dampers combine a piston and ball, and some have only a piston.
Operation of Piston-and-Ball Type
- When a pressure...

Operation Section1–49
(4) Pressure Discharge Valve
• The pressure discharge valve controls the fuel pressure in the rail. When rail fuel pressure exceeds the target injection
pressure, or when the engine ECU judges that rail fuel pressure exceeds the target value, the pressure discharge
valve solenoid coil is energized. This opens the pressure discharge valve passage, allowing fuel to leak back to the
fuel tank, and reducing rail fuel pressure to the target pressure.
Q000861E
Pressure Discharge Valve...

Operation Section1–50
5. INJECTOR DESCRIPTION
5.1 General Description
zThe injector injects the pressurized fuel in the rail into the engine combustion chamber at the optimal injection timing,
injection quantity, injection rate, and injection pattern, in accordance with signals from the ECU.
zInjection is controlled using a TWV (Two-Way Valve) and orifice. The TWV controls the pressure in the control chamber
to control the start and end of injection. The orifice controls the injection rate by restraining...

Operation Section1–51
5.2 Injector Construction and Features
zThe injector consists of a nozzle similar to the conventional nozzle & nozzle holder, an orifice that controls the injection
rate, the command piston, and a TWV (two-way solenoid valve). The basic construction is the same for the X1, X2, and
G2 types.
(1) X1 Type
• Precision control is attained through electronic control of the injection. The TWV comprises two valves: the inner valve
(fixed) and the outer valve (movable).
Q000863E
Nozzle...

Operation Section1–52
(2) X2 Type
• By reducing the injector actuation load, the injector has been made more compact and energy efficient, and its injec-
tion precision has been improved. The TWV directly opens and closes the outlet orifice.
Control 
Chamber Solenoid 
Va l v e Hollow Screw with Damper
O-ring
Command Piston
Nozzle Spring
Pressure Pin
Nozzle Needle Seat
High-Pressure Fuel
Leak PassageFrom Rail
Q000864E 

Operation Section1–53
(3) G2 Type
• To ensure high pressure, the G2 type has improved pressure strength, sealing performance and pressure wear re-
sistance. It also has improved high-speed operability, enabling higher-precision injection control and multi-injection.
< NOTE >
Multi-injection means that for the purpose of reducing exhaust gas emissions and noise, the main injection is accom-
plished with one to five injections of fuel without changing the injection quantity.
Q000865E
Connector
Solenoid...

Operation Section1–54
5.3 Injector Operation
zThe injector controls injection through the fuel pressure in the control chamber. The TWV executes leak control of the
fuel in the control chamber to control the fuel pressure within the control chamber. The TWV varies with the injector type.
Non-Injection
• When the TWV is not energized, the TWV shuts off the leak passage from the control chamber, so the fuel pressure
in the control chamber and the fuel pressure applied to the nozzle needle are both the same...

Operation Section1–55
5.4 Injector Actuation Circuit
zIn order to improve injector responsiveness, the actuation voltage has been changed to high voltage, speeding up both
solenoid magnetization and the response of the TWV. The EDU or the charge circuit in the ECU raises the respective
battery voltage to approximately 110V, which is supplied to the injector by signal from the ECU to actuate the injector.
Q000868E
INJ#1 (No.1 Cylinder)
ECU InjectorINJ#2 (No.3 Cylinder)
INJ#3 (No.4 Cylinder)
INJ#4 (No.2...