WÄRTSILÄ 41508, Инструкция по эксплуатации

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15.C.0.2 Function
The wastegate control system gets compressed air from the instrument
air system. The pressure is approx. 6 - 7 bar. The instrument air needs to
be clean, dry and oil free to secure the function of the components. See also
chapter 21.
The wastegate system works as follows:
When the engine is running, the valve (6) is open and supplies air to
the I/P converter (8) and to the positioner (9) in the actuator unit (1).
The I/P converter maintains a 0.2 - 1.0 bar control air pressure to the
positioner according to the incoming 4 - 20mA control signal.
The positioner pilot valve (11), see Fig 15C-4, maintains the actuator
(1) with air pressure according to the control air pressure from the I/P
converter.
The engine control system (WECS) is monitoring the average exhaust
gas temperature after the cylinders. If the average exhaust gas tem-
perature is higher than the set-point, the engine control system will
close the wastegate gradually, until tye correct value is reached.
The main purpose of the solenoid valve (6) is to prevent air leakage
through the I/P converter to the actuator when the engine is stopped.
The control logic is carried out in the engine control system and no
external regulators are required
15.C.0.3 Maintenance
15.C.0.3.1
Check of wear of the wastegate system
The systems requires a regular check of the wear and the function.
1 Check for wear of the key connection
between the actuator
and the positioner.
2 Check for possible wear inside actuator by moving the
shaft.
15.C.0.3.2
Change of positioner pilot valve
The pilot valve (11) in the positioner should be replaced with a new one
according to chapter 04 or in case of malfunction.
1 Remove the cover of the positioner
and the pilot valve screws
(12), see Fig 15C-2.
2 Pay attention to the pilot valve stem and the lever (13), re-
move the pilot valve carefully.
3 Replace the pilot valve (11) with a new one and re-assemble
the positioner in the opposite order.
4 Adjust the wastegate positioner, see section 15.C.0.4.
5 Calibrate the wastegate I/P converter, see section 15.C.0.5.
6 Check the function
of the valve by following the positioners
Appendix C Turbocharging and Air Cooling 32-200247