DV11
Operation and Maintenance
127
Common Rail Fuel-injection System
Printed in Mar. 2005 PS-MMA0608-E1A
exerts no downwards-acting forces on the armature and the ball.
The closing of the bleed orifice leads to pressure buildup in the control chamber
via the input from the feed orifice. This pressure is the same as that in the rail and
exerts an increased force on the control plunger through its end face. This force,
together with that of the spring, now exceeds the force exerted by the chamber
volume and the nozzle needle closes.
The nozzle needle's closing speed is determined by the flow through the feed
orifice. Injection ceases as soon as the nozzle needle comes up against its
bottom stop again.
3.4.14. Crank shaft speed sensor
z
The piston position in the combustion
chamber is decisive in defining the
start of injection. All the engine's
pistons are connected to the
crankshaft by connecting rods. A
sensor on the crankshaft can therefore
provide information on the position of
all the pistons. The rotational speed
defines the number of crankshaft rotations per minute. This important input
variable is calculated in the ECU using the signal from the inductive crankshaft
speed sensor.
3.4.15. Cam shaft speed sensor
z
The camshaft controls the engine's
intake and exhaust valves. It turns at
half the speed of the crankshaft. When
a piston travels in the direction of TDC,
the camshaft position determines
whether it is in the compression phase
with subsequent ignition, or in the
exhaust phase. This information cannot
be generated from the crankshaft position during the starting phase. During
normal engine operation on the other hand, the information generated by the
crankshaft sensor suffices to define the engine status. In other words, this means
that if the camshaft sensor should fail while the vehicle is being driven, the ECU
still receives information on the engine status from the crankshaft sensor.
Shim
Crank Shaft
Sensor
Fixing Bolt
Shim
Crank Shaft
Sensor
Fixing Bolt
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