WÄRTSILÄ Vasa R22, Instruction Manual

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fuel rack is connected to the regulating mechanism of the gover-
nor. If the fuel rack is moved, the control sleeve in mesh with the
rack is turned. Since the control sleeve acts on the plunger, the
plunger turns with the control sleeve, thus the effective stroke
changes and the injected fuel amount increases or decreases.
The element is of a mono-block design with integrated fuel
delivery valve and constant pressure valve. The ports are of a
special design to prevent cavitation.
The delivery valve, provided in the top of the element, performs
the function of discharging the pressurized fuel to the injection
pipe. The fuel compressed to a high pressure by the plunger forces
the delivery valve to pop up. Once the effective stroke of the
plunger ends, the delivery valve is brought back to its original
position by the spring and blocks the fuel path, thereby prevent-
ing counter flow of the fuel.
After the effective stroke, the fuel is drawn back through the
constant pressure valve from the high pressure injection pipe to
instantly lower the residual pressure between the delivery valve
and the nozzle. This draw-back effect improves the termination
of an injection on the nozzle and prevents after injection dripping.
16.2.2 General description
The injection pump body consists of a cast housing provided with
flanges for fastening against the engine block. The tappet with
roller is located at the bottom of the housing. The roller rolls
against the injection cam of the camshaft under the pressure of a
spring (17). Between the tappet and the plunger there is a disc
(28) against which the plunger end is pressed.
The pump element, of the mono-element type, is included in the
top part of the housing and consists of a plunger (8) and a cylinder
(7) which are matched between themselves and should be treated
as a unit. The upper part, i.e. the fuel side, is sealed from below
by O-rings (24). The element cylinder is pressure lubricated,
which prevents fuel from penetrating downwards and mixing
with lubricating oil.
The fuel delivery control, i.e. the rotary motion of the plunger,
is actuated by a control rack through a control sleeve (14).
The delivery valves are located in the upper part of the element
and in the head piece. The sealing element cylinder-head piece is
metallic, see Fig 16-1.
16.3 Maintenance of injection pump
Most maintenance operations can be done without removing the
injection pump from the engine. It is recommendable that the
engine will be run 5 minutes with light fuel before stopped for
overhaul of injection pump. During maintenance utmost cleanli-
ness must be observed.
16 Injection System 22-9601
16-2 L’Orange