Principle of Variable Valve Timing Technology

The valve timing system of a traditional engine is a mechanical system in which the valve opening and closing phases are fixed, which makes it difficult for the system to meet the needs of the engine in a variety of working conditions, and fails to meet the requirements of the engine to produce strong power at various speeds. The variable valve timing system is an electronically controlled system that changes the valve opening time or opening size. By matching the vehicle with more reasonable valve opening or closing moments at different speeds, it enhances the balance of the vehicle's torque output, increases engine power and reduces the vehicle's fuel consumption.

From the air-matching phase diagram, it can be seen that during the intake process when the piston moves from the top stop to the bottom stop, the intake valves will open earlier and close later. When the engine has completed its work and the piston moves from the lower stop to the upper stop during the exhaust process, the exhaust valve opens early and closes late.

This practice of extending the valve opening time will inevitably lead to a moment when the intake and exhaust valves open at the same time, which is known as the "overlap phase" on the gas distribution phase, and may result in exhaust gas backflow. This phenomenon is most noticeable at idle speeds when the engine speed is just under 1,000 r/min (the duration of the "overlap phase" is seven times longer at idle than at moderate speeds). This tends to cause poor idling, excessive vibration, and power loss. Especially in the case of four-valve engines, the "overlap phase" is more likely to cause poor idling due to the large value of the "curtain zone". In order to eliminate this defect, the designers adopted a "variable" valve actuator to counteract the "change".

Variable valve actuator is to reduce the valve stroke and narrow the "curtain area value" when the engine is working at a rapid speed, and increase the valve stroke and expand the "curtain area value" when the engine is working at a high speed, changing the time of the "overlap phase", which is the time of the "overlap phase", and the time of the "overlap phase". Overlap phase" time, so that the engine can provide strong power at high speeds, and at low speeds can produce enough torque, thus improving the performance of the engine. The valve variable drive mechanism can change the gas distribution phase at any time according to the operating conditions of the car, changing the valve lift and the duration of valve opening.