High-Pressure Rail; Checking Pressure Control Valve (Drv); At High-Pressure Rail - Bosch CRS 845H Instandsetzungsanleitung

en 52 | CRS 845H | Trouble-shooting
In the event of a fault:
1
4
1 - 5 mm
Fig. 18: Safety switch installation position
1 Actuator
2 Safety switch
3 LED
4 Positioning surface
1. Check and if necessary adjust the distance between
the safety switch (Pos. 2) and the actuator (Pos. 1).
Make sure the flats (Pos. 4) at the safety switch and
actuator are in alignment.
Assured distance: 1 to 5 mm
Tightening torque of nut: 3 Nm
2. Check the 12 V power supply at connector X14 on
the trigger PCB (A10).
Pin 4 12 V
⊥
Pin 5
If the 12 V power supply is not OK:
Check the power supply of the trigger PCB
(refer to Section 5.1).
3. Detach the connecting cable 1 687 465 486 from the
connector X14.
4. Continuity check
Pin 1 Pin 4
Pin 2 Pin 4
Pin 3 Pin 4
If there is no continuity:
Check the connecting cable 1 687 465 486
for continuity.
or
Check the connection between connector X2 and the
24 V emergency stop switching device 3A1.
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5.3

High-pressure rail

5.3.1

Checking pressure control valve (DRV)

at high-pressure rail

The function of the pressure control valves is to
generate and maintain the pressure required in the
high-pressure rail. All three pressure control valves are
fitted in the high-pressure rail and are connected in
parallel.
Mode of operation:
Inside one pressure control valve is an armature which
is depressed by a spring. The armature presses a ball
into a sealing seat, thus sealing off the high-pressure
end from the low-pressure end. The spring force may
also be assisted by a solenoid acting on the armature.
If the pressure control valves are not actuated, i.e. the
solenoid remains de-energized, the force of the high
pressure in the rail acts in opposition to the spring
force with the result that the pressure control valves
remain open to a greater or lesser extent depending
on the pump delivery rate. If the pressure in the rail is
to be increased, the magnetic force must be built up
in addition to the spring force. The pressure control
valves are actuated (energized) and thus closed until
equilibrium is established between the force of the high
pressure on one side and the magnetic and spring force
on the other. They then remain in open position and
keep the pressure in the rail at a constant level.
Electrical checking:
1. Detach the connecting cable at the DRV.
2. Connect a digital multimeter to the two blade termi-
nals of the DRV and measure the internal resistance.
i
Do not check the internal resistance with the DRVs
warm. Allow the DRVs to cool down to ambient
temperature.
Internal resistance 4.2 ohms
Tolerance ± 1 ohm
In the event of a fault:
Replace DRV.
Robert Bosch GmbH