Advance Variator Operating Principle; Injection Timing Device Operation - Kohler KD 625/3 Workshop Manual

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ADVANCE VARIATOR OPERATING PRINCIPLE

INJECTION TIMING DEVICE OPERATION

In order to meet EPA tier 2 limits, the engine KD 625-3 has been equipped with a variable injection timing device.
The system consists of an electro–hydraulic actuated mechanical device, that allows changing the injection timing by rotating
the camshaft against its driving gear.
The change takes place using the oil whose pressure is regulated by a pair of electric valves, which allow a rotation between 0
and 4.5°. The maximum variation of the injection timing is 4.5° (camshaft degrees).
Oil is taken from the engine oil circuit and its pressure acts on a sort of hydraulic piston that moves from one side to the other.
The hydraulic plunger is attached on the inside by means of a straight groove and on the outside via a spiral-shaped groove.
Thus movement from left to right (or vice versa) causes rotation from the driving gear and the camshaft.
In other words, the plunger translates and, at the same time, rotates and thus varying the angular position of camshaft that is
connected to it.
The gear timing variation is managed by an ECU which receives electric signals from two speed sensors, the temperature sen-
sor and the load sensor, which reads the position of the injection pump control.
The ECU memory contains the maps of the injection timing variation strategies.
Fig. A_1. Injection timing device: in "Resting position"
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KD Workshop Manual_cod. ED0053029350_1° ed_ rev. 00