Operation
2728−1/A1
Winterthur Gas & Diesel Ltd.
1/ 2
Starting Valve
1. General
A starting air valve is installed in each cylinder cover (5, Fig. 1). The starting air valves
start the engine, or decrease the engine speed for reversing.
The Wärtsilä Engine Control System (WECS-9520) monitors and controls the starting
air valve operation (see 4002−1, paragraph 4.4). FCM-20 open the starting air valves
electronically at the correct crank angle to release starting air into the combustion
chamber.
The parameter settings of the starting air valves are adjustable. The remote control of
the WECS-9520 gives access to the parameter settings (see 4618−1, Local Control
Panel, paragraph 2.2).
For data to vent the starting air manifold, see 0320−1, paragraph 1.2.2.
For more data, see the schematic diagram in 4003−2.
2. Function
2.1 Initial Conditions
Starting air pressurizes the space (S2). The compression spring (4) keeps the valve
closed. The connection (CA) at the cover (1) has starting air pressure.
2.2 Engine Start
The FCM-20 activates the 3/2-way solenoid valve (7). The space (S
1
) is pressurized,
the valve opens and starting air flows into the combustion chamber. The piston (2)
moves down, starting air flows into the combustion chamber and the engine starts to
turn.
When combustion starts, the higher pressure (firing pressure) in the combustion
chamber keeps the starting air valve closed.
2.3 Engine Slow-down (to Reverse the Engine)
If the combustion and thus the propulsion stops (or a slower speed is selected from
the remote control), the movement of the ship continues. The flow of water has a drag
effect on the propeller.
To start the engine in the opposite direction, it is necessary to slow down the engine
speed below the set limit. This operation is related to the engine speed and propeller
configuration and can be some minutes.
At the specified engine speed, the WECS-9520 opens the starting air valve at
approximately 100_ before TDC. The starting air flows into the combustion chamber.
The piston in the cylinder moves up, compresses the air and the engine speed
decreases and stops.
The engine starts, then turns in the opposite direction. For more data about reversing,
see 0260−1 Maneuvering.
2014
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