WÄRTSILÄ 46DF Product Manual Download

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4.2.9

Camshaft and valve mechanism

The camshaft is built of forged pieces with integrated cams, one section per cylinder. The
camshaft sections are connected through separate bearing journals, which makes it possible
to remove single camshaft sections sideways. The bearing housings are integrated in the
engine block casting and thus completely closed.

4.2.10

Camshaft drive

The camshaft is driven by the crankshaft through a gear train. The gear wheel on the crankshaft
is clamped between the crankshaft and the end piece with expansion bolts.

4.2.11

Fuel injection equipment

The Wärtsilä 46DF engine is designed for continuous operation on fuel gas (natural gas) or
Marine Diesel Fuel (MDF). It is also possible to operate the engine on Heavy Fuel Oil (HFO).
Dual fuel operation requires external gas feed system and fuel oil feed system. For more details
about the fuel system see chapter Fuel System.

4.2.11.1

Fuel gas system

The fuel gas system on the engine comprises the following built-on equipment:

Low-pressure fuel gas common rail pipe

Gas admission valve for each cylinder

Safety filters at each gas admission valve

Common rail pipe venting valve

Double wall gas piping

The gas common rail pipe delivers fuel gas to each admission valve. The common rail pipe is
a fully welded double wall pipe, with a large diameter, also acting as a pressure accumulator.
Feed pipes distribute the fuel gas from the common rail pipe to the gas admission valves
located at each cylinder.

The gas admission valves (one per cylinder) are electronically controlled and actuated to feed
each individual cylinder with the correct amount of gas. The gas admission valves are controlled
by the engine control system to regulate engine speed and power. The valves are located on
the cylinder head. The gas admission valve is a direct actuated solenoid valve. The valve is
closed by a spring (positive sealing) when there is no electrical signal. With the engine control
system it is possible to adjust the amount of gas fed to each individual cylinder for load
balancing of the engine, while the engine is running. The gas admission valves also include
safety filters (90 µm).

The venting valve of the gas common rail pipe is used to release the gas from the common
rail pipe when the engine is transferred from gas operating mode to diesel operating mode.
The valve is pneumatically actuated and controlled by the engine control system.

The fuel gas fine filter is a full flow unit preventing impurities from entering the fuel gas system.
The fineness of the filter is 5 µm absolute mesh size (0.5 µm at 98.5% separation). The filter
is located in the external system if double wall gas piping is used.

4.2.11.2

Main fuel oil injection

The low pressure fuel lines consist of drilled channels in cast parts that are firmly clamped to
the engine block. The entire fuel system is enclosed in a fully covered compartment for
maximum safety. All leakages from injection valves, pumps and pipes are collected in a closed
system. The pumps are completely sealed off from the camshaft compartment and provided
with drain for leakage oil.

The injection nozzles are cooled by lubricating oil.

DBAD209883

4-3

4. Description of the Engine

Wärtsilä 46DF Product Guide