1-M18
BX1800 · BX2200, WSM
ENGINE
■ Delivery Valve
The delivery valve consists of the delivery valve (1)
and delivery valve seat (2).
The delivery valve performs the following functions.
1. Reverse flow preventing function
If the fuel flow reverse from the injection nozzle side
when the plunger lowers, the time lag between the next
delivery start and the nozzle injection start increases. To
avoid this, the delivery chamber to injection pipe
interruption by delivery valve (1) prevents this reverse
flow, thus keeping fuel always filled in the nozzle and
pipe.
2. Suck-back function
After completing the fuel delivery, the delivery valve
lowers, and the relief plunger (4) end contacts the
delivery valve seat (2). The valve further lowers until its
seat surface (3) seats firmly the delivery valve seat.
During this time, the amount of fuel corresponding to (A)
is sucked back from inside the injection pipe, the
pressure inside the pipe is reduced, thus leading to an
improved injection shut off and preventing after leakage
dribbling.
W1018594
■ Dumping Valve
1. At fuel injection
Since dumping valve is pushed up to press the spring,
fuel is pressure-fed to injection nozzle the same as
without dumping valve.
2. At suck-back
At suck-back by delivery valve after fuel injection fuel
returns through dumping valve orifice. Generally second
injection is apt to occur by reflex pressure due to reaction
of sudden pressure drop when changing into suck-back
by delivery valve from high injection pressure.
As a result of preventing this second injection
perfectly by dumping valve and dissolving nozzle
clogging, durability of injection nozzle is improved.
W1018873
(1) Delivery Valve
(2) Delivery Valve Seat
(3) Seat Surface
(4) Relief Plunger
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