ACTUATOR
FUEL FLOW REGULATOR
Role
Description
- The piston is retained at he base of its location
by means of the spring
- The connection between the 2 pipes is open
- The inlet to the high pressure stage of the high pressure fuel pump is open
- The fuel is directed to the high pressure stage of the high pressure fuel pump
- The fuel flow regulator electric coil drives
the magnetic core (magnetic force)
- The piston moves
- The connection between the 2 pipes is closed
- The fuel is directed towards the high pressure fuel regulator valve
Special features
Variable voltage control (OCR)
- Maximum voltage Injection of expanding foam = Maximum fuel flow
- Minimum voltage Injection of expanding foam = Minimum fuel flow
note | OCR: Open cycle ratio |
HIGH PRESSURE FUEL REGURATOR
Role
Description
Control
- The fuel high pressure opposes the action
of the magnetic core and ball
- The fuel released by the high pressure fuel regulator returns to the fuel tank
- The engine-ECU controls the high pressure
fuel regulator by reducing the frequency of the OCR signal
- The coil of the high pressure fuel regulator drives the magnetic core (magnetic force)
- The fuel return closes
- The force applied to the ball and the magnetic force of the core is higher than
the pressure in the fuel high pressure common injection rail
- The high pressure fuel regulator cut-off valve increases
- The engine-ECU increases the frequency of
the OCR signal supplied to the high pressure fuel regulator coil
- The coil of the high pressure fuel regulator drives the magnetic core (magnetic force)
- The fuel return opens
- Te force applied to the ball and the magnetic force of the core is lower than the
pressure in the fuel high pressure common injection rail
- The cut-off valve of the high pressure regulator decrease
note | OCR: Open cycle ratio |
Special feature
Variable voltage control (OCR)
- OCR 100 %: High pressure fuel regulator open, minimum pressure
- OCR 0 %: High pressure fuel regulator closed, maximum pressure
FUEL INJECTOR
Role
- Pre-injection in order to reduce the operating
noise and to diminish the polluting emissions
- Main injection
- Post-injection for heating the exhaust gases in order to enhance the filtration
of the particles
Description
Principle of opening and closing of the diesel injector
· Opening principle of a diesel injector
- The additional supply duct opening (1) closes
and the leak-off opening (2) opens
- The equilibrium between the pressure of the control chamber and the pressure chamber
is broken
- The pressure present in pressure chamber lift the diesel injector needle
- The control piston lifts up
- The fuel in sent to the top of the piston
note | The injection of fuel last as long as the piezo-electric actuator is not released. |
· Closing principle of a diesel injector
- The spring of the diesel injector needle holes
the closing end pad its seat
- The additional supply duct opening opens and the leak-off opening closes
- The rise in pressure in the control chamber causes the diesel injector to close
- The fuel fills the chamber above the needle via the additional duct and via the
conventional supply opening
- The equilibrium of pressure is re-established between the control chamber and the pressure
chamber
- The diesel injector is ready for a new cycle
Number of injections per cycle
- 2 pilot up to 3,200 r/min (Then 1 up to 4,500
r/min)
- 1 Main
- 2 post injections depending on the vehicle load (During the regeneration phase)
Strategies used
- Hydraulic compensation
- Adaptation of the pilot injection for each diesel injector
- Regulation of the place to place flow
- Lowering of the fuel pressure (protection of the fuel circuit)
- On the conventional piezo-electric diesel injectors,
there is an operating clearance between the actuator and the mushroom valve, to compensate for
the variations linked with the thermal expansion of the parts.
Over time, this clearance tends to increase.
When the injection ends, any clearances are compensated.
The thrust rod spring exerts a pressure which tends to increase the volume of the hydraulic chamber.
If the clearances have increased, a corresponding quantity of diesel fuel infiltrates via the internal leak-offs of the thrust rod to compensate for them.
The guarantee the operation of the diesel injector, this remains full of diesel fuel so that the hydraulic chamber of the thrust rod does not empty.
A valve incorporated in the global return pipe of the 4 diesel injectors provides this function by maintaining a pressure of 10 bars.
- Principle of analysis of the acceleration of the crankshaft
when the pedal is released.
Individual adaptation of the pilot injection.
The engine-ECU measures the acceleration of the crankshaft obtained by injecting very small pilot quantities, each time the pedal is released.
Depending on the results, the engine-ECU increases or reduces the quantities injected (diesel injector control time) until the acceleration corresponds to a typical graph pre-recorded in the memory of the engine-ECU.
The engine-ECU analyses the corrections to be made to the control of each diesel injector.
- Principle of analysis of the acceleration of the crankshaft
at idle.
Management of the place to place flow.
The engine-ECU measures the acceleration of the crankshaft during the pressure relief phase when the engine is at idle and at low engine speeds.
The engine-ECU then adjusts the control of the diesel injectors (main injection) to obtain identical accelerations; the aim being to obtain a great regularity of operation.
- Principle of analysis of the diesel fuel temperature.
In order to protect the high pressure pump and the components of the fuel circuit, the temperature at the high pressure fuel pump inlet must remain below 70°C.
If the temperature exceeds this value, the fuel pressure is lowered to reduce the temperature of the diesel fuel.
Injector ID code |
VARIABLE GEOMETRY CONTROL MOTOR |
THROTTLE VALVE CONTROL MOTOR |
SWIRL CONTROL SOLENOID VALVE |
EGR VALVE (DC MOTOR) |
Refer to GROUP 17 - Emission Control <Diesel> - Exhaust Gas Recirculation
(EGR) System <4HN> . |
EGR COOLER SOLENOID VALVE |
Refer to GROUP 17 - Emission Control <Diesel> - Exhaust Gas Recirculation
(EGR) System <4HN> . |