Page 261 - Foton Workshop Manual - Aumark (BJ1099)

ENGINE CONTROL SYSTEM - OCV VALVE 11-35
OCV VALVE

1. Principle of work
The working power supply of the intake VVT solenoid valve is provided by the main
relay and ECM modulates the signal control grounding with pulse width Therefore,
to control the oil flow of the engine flows towards the camshaft position actuator.
Oil pressure is a safe slide valve action inside the camshaft position actuator, which
is fixed in front of the camshaft. In the process of the safe slide valve action, oil is
channeled into the camshaft position actuator to rotate the camshaft. The continual 11
change of the phase between camshaft and crankshaft can control the valve timing.
2. Function and installation
According to the rotation speed of engine, load, temperature of cooling water, etc.,
ECU confirms the camshaft phase required and sends duty ratio signal to OCV
valve. OCV valve is a solenoid valve of four-access pulse width modulation with the
ability of bidirectional movement. According to the control signal of ECU, it changes
the axial displacement of the slide valve and controls the oil flow and the flowing
direction of the oil towards VVT.
OCV valve is installed on the intake side of cylinder head.
3. Fault phenomenon and judgment method
(a). Fault phenomenon: VVT cannot reach the targeted phase angle.
(b). General causes for faults:
The seal ring on the surface of OCV valve is damaged, which will lead to oil
pumping between oil passages, and the short circuit or open circuit of OCV coils.
(c). Precautions for maintenance:
• Avoid knocking in the process of installation, and check whether the strainer filter
is clean and intact without obvious granules, whether the O-type ring is in good
condition, and whether the seal ring is scratched seriously, or else the installation
cannot be implemented.
• Check whether the slide valve of OCV is on the fully closed position, or else it
cannot be used.
• Before installation, lubricate the O-type ring with oil, and then push the OCV valve
into the mounting holes of the cylinder head carefully till the mounting surface is
connected with the cylinder head, and at last, tighten the bolt.
• Clean the OCV valve with clean oil rather than oil of powerful solvent (e.g.
gasoline), nor can it be blew by compressed air.If OCV valve is pasted with oils
except for the engine oil, it should be cleaned promptly.
• The slide valve and the head of connectors are not allowed to be dipped by water.

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