DAF CF65, Service Manual

Page: 73 / 352

©
200416 3-1
Description of components
CE ENGINE FUEL SYSTEM
ΧΦ65/75/85
series
4
2
3. DESCRIPTION OF COMPONENTS
3.1 HIGH-PRESSURE PUMP
The high-pressure pump is driven by the
crankshaft by means of the camshaft gear. The
pump shaft rotates at a speed 1.33 times the
speed of the crankshaft. The pump shaft drives
the fuel lift pump. The fuel drawn from the suction
side by the gears is discharged through the exit
by the gears due to the reduction in volume. The
fuel lift pump has two added valves. The first
valve (1) limits the pump pressure, for example if
the fine filter is blocked. The second valve (2)
opens the by-pass over the fuel lift pump when
the primer pump is being used.
The high-pressure pump shaft (1) has an
eccentric. The eccentric drives the eccentric
ring (4). The pump plungers (3) are driven by the
eccentric ring and pushed back by the spring (2).
The fuel is supplied via the connection (5) and
then internally distributed among the three pump
elements. Before it is distributed among the pump
elements, the supplied fuel is dosed by means of
the fuel pump control solenoid valve (6).
The fuel pump control solenoid valve is controlled
by the electronic unit on the basis of the rail
pressure sensor signal. This creates a closed
control circuit. The fuel pump control solenoid
valve is "normally open" and is activated via duty
cycle control. The value when the engine is
started is fixed. When the measured pressure
deviates from the desired (programmed)
pressure, the duty cycle value will be adapted
until the measured and the desired values
correspond. If this is impossible, the electronic
unit will generate a warning and record a fault
code.
1 2
B
A
i400595
7
5
4
2
3
1
i400589
6
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