Index

Page 1 (1)

Cyl. 1

Fuel oil feed pump

Waste tray

Drain from cyl. head

Leak from fuel pump

Fig. 1. Diagram for Fuel Oil System

General

The internal built-on fuel oil system consists of the following parts:

-the fuel oil feed system

-the high-pressure injection equipment, comprising fuel oil injection pumps, fuel oil injection valve and fuel oil high pressure pipe

-the waste oil system

Internal Fuel Oil Feed System

The fuel oil is led to the injection pumps through a safety filter by means of the engine driven feed pump (if part of the delivery).

The safety filter is a duplex filter of the split type with a filter fineness of 50 my. The filter is equipped with a common three-way cock for manual change of both the inlet and outlet side.

During normal operation both filters should be in operation. Single operation only to be used when dismantling one of the filters for manual cleaning or inspection.

The feed pump (if part of the delivery,) which is of the gear wheel type, is equipped with a spring-loaded adjustable by-pass valve.

The outlet pressure of the feed pump can be adjusted by means of an adjusting screw in the by-pass valve assembly.

L23/30H

For circulation of fuel during stand-still of the engine, a by-pass line is mounted with a non-return valve parallel to the feed pump.

Fuel Injection Equipment

Each cylinder unit has its own set of injection equipment, comprising injection pump, high-pressure pipe and injection valve.

The injection equipment and the distribution supply pipes are housed in a fully enclosed compartment thus minimizing heat losses from the preheated fuel.

This arrangement reduces external surface temperatures and the risk of fire caused by fuel leakage.

Fuel Oil Injection Pump

The fuel oil injection pump is installed on the roller guide housing directly above the camshaft, and it is activated by the cam on the camshaft through roller guides fitted in the roller guide housing.

The injection amount of the pump is regulated by transversal displacement of a toothed rack in the side of the pump housing.

By means of a gear ring, the pump plunger with the two helical millings, the cutting-off edges, is turned.

Hereby the length of the pump stroke is reckoned from when the plunger closes the inlet holes until the cutting-off edges again uncover the holes.

The release of high pressure through the cutting-off edges presses the oil with great force against the wall of the pump housing. At the spot, two exchangeable plug screws are mounted.

The amount of fuel injected into each cylinder unit is adjusted by means of the governor.

It maintains the engine speed at the preset value by a continuous positioning of the fuel pump racks, via a common regulating shaft and spring-loaded linkages for each pump.

The injection valve is for "deep" building-in to the centre of the cylinder head.

Fuel Oil Injection Valve

The fuel oil injection valve consists of a nozzle holder and a nozzle connected by a union nut. The nozzle holder includes a threaded pipe stub for mounting the high-pressure pipe. It is led through a boring in the cylinder head, together with an adjusting screw, a spring and spring spindle for the initial tensioning of the nozzle needle.

The initial tension of the spring, which determines the opening pressure of the nozzle, can be adjusted by means of the centrally-mounted adjusting screw.

On the uppermost thick part of the holder, there are three sealing O-rings.

Between the two lowest O-rings, the leak oil from the nozzle needle is led out into the space between the high-pressure pipe and the protection tube.

The nozzle and needle are lapped together as a pair, and cannot be replaced individually. The nozzle is controlled by two pins attached to the bottom of the holder.

The joint surface between the nozzle and holder is machine-lapped to make it oil-tight.

The fuel injector is mounted in the cylinder head by means of the integral flange in the holder and two studs with distance pieces and nuts.

A bore in the cylinder head vents the space below the bottom rubber sealing ring on the injection valve, thus preventing any pressure build-up due to gas leakage, but also unveiling any malfunction of the bottom rubber sealing ring for leak oil.

The connection between injection pump and fuel injector is a shielded high pressure pipe. The high pressure pipe is equipped with connection tapers matching to simiular taper facings on the threaded connectors on the injection pump and the fuel injector.

Waste leak oil from the compartment, fuel valve and engine feed pump is led to a fuel leakage alarm unit.

The alarm unit consists of a box with a float switch for level monitoring. In case of a larger leakage than normal leakage, the float switch will initiate alarm. The supply fuel oil to the engine is led through the unit in order to keep this heated up, thereby ensuring free drainage passage even for high-viscous waste/ leak oil.