DV11
Operation and Maintenance
117
Common Rail Fuel-injection System
Printed in Mar. 2005 PS-MMA0608-E1A
z
At the beginning of the injection process, the injected fuel quantity should be as
low as possible (that is, during the ignition lag between the start of injection and
the start of combustion)
z
The common rail system is a modular system, and essentially the following
components are responsible for the injection characteristic.
- Solenoid valve controlled injectors which are screwed into the cylinder head
- Common rail
- Fuel high pressure pump
- Electric control unit(ECU)
- Crankshaft speed sensor
- Camshaft speed sensor
3.4.4. Fuel high pressure pump
z
A radial-piston pump is used as the high pressure pump for pressure generation.
Pressure is generated independently of the injection process. The speed of the
high pressure pump is coupled directly to the engine speed with a non-variable
transmission ratio. In comparison with conventional injection systems, the fact
that delivery is practically uniform.
z
The injectors are connected to the common rail by high pressure pipe, comprise a
nozzle, and a solenoid valve which is energized by the ECU to switch it on (start
of injection), When the solenoid valve is switched off injection ceases.
Time t
Time t
Injectio
n press
ure P
Injectio
n press
ure P
Start of delivery
Start of injection
Fuel injection
Ps
Pm
P
R
(Pm)
Fuel injection of injection pump
Pm : Main injection pressure
Ps : Max. injection pressure
Common rail fuel injection
Pm : Main injection pressure
Ps : Max. injection pressure
Downloaded from
www.Manualslib.com
manuals search engine