Delivery Valve
The delivery valve is composed of the valve and the valve seat. It performs two functions:
1.
Reverse flow prevention:
If the circuit between the delivery chamber and the nozzle is always closed, a time lag will
occur between pressure feed start of valve element and start of nozzle injection. This,
in
turn, will prevent injection from stopping properly until after completion of pressure-feed.
To
eliminate this time lag, the valve lowers
on
completion of pressure-feed and the relief
valve
contacts the valve seat, and breaks the circuit between the injection pipe and
plunger.
2.
Fuel dribbling prevention:
After the
relief valve contacts delivery valve seat, this valve lowers a little. Since the relief
valve
breaks the circuit pressure int
he
injection pipe is reduce
as
the valve lowers,
preventing fuel dribbling from the nozzle.
Pump Element
The pump element is composed of a cylinder and a plunger. Their contact surfaces are
precision finished to provide a high injection pressure even at
low speeds. The cylindrical
surface of the plunger has slanted grooves, which are called control grooves, and a
connecting
hole for plunger head.
Control Rack
This is connected directly to the governor fork in the engine body. It is connected with the
plunger by pinion to change injection volume.
Tappet
The tappet converts rotating movement of the camshaft into a reciprocating movement to
drive
plunger. A roller is used where it contacts the cam to reduce friction.
Delivery Velve
Pump Element
(8)
(7)
(9)
(5)
(6)
1. Relief Valve
2. Seat
3. Delivery Valve Seat
4. Pressure Decrease Because
of
Increase
in
this Volume
5. End of Pressure-feed and Start
of
Sucking Back
6. End of Sucking Back
7.
Pump Element
8. Cylinder
9. Plunger
10. Feed Hole
11.
Control Groove
12. Driving Face
65
(10)
(11)
(12)
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