Variable valve timing

Variable valve timing is continuously modifies the phase of the actuator and the variable valve timing camshaft drive under the influence of the intake valves of the hydraulic pressure, which is controlled by the oil control valve (OCV) so that the phase of opening and closing valves optimally match the operating conditions of the engine. Work the oil control valve (OCV) based on the signals from the camshaft position sensor according to the conditions of the engine. It controls the hydraulic pressure acting on the actuator variable valve timing.

The operation according to traffic conditions: idle, small load

By reducing the overlap is less than the combustion products back into the cylinder. This stabilizes the idling speed, improving fuel efficiency, and ensures stable operation of the engine at low loads.

Average load

Overlapping increases, and the ratio of EGR in the cylinder - grows. This reduces the friction loss (pumping loss) is reduced and the combustion temperature reduces the amount of CO in the exhaust gases. Emissions of hydrocarbons are also reduced due to not re-ignited gas afterburning.

High load, low and average speed

The inlet valves are closed early, which ensures a high volume. N. D., Thereby improving the torque at low and medium speeds.

Most of the load, the range of high speeds

The intake valve closes later to the high volume. N. D. Provides maximum power.

At low temperatures

Overlapping minimized to prevent combustion in the cylinders and to reduce the amount of supplemental fuel injected into the cylinders. This improves fuel efficiency and stabilize higher idle speed.

When starting or stopping the engine

Startability is improved owing to reduction of overlap, since the products of combustion are not returned to the cylinder.

Table 2.12 Elements and their functions