What does variable valve timing mean?

[DiSpencer]

Variable valve timing is a technology used in automotive piston engines. VVT technology can adjust the overlap time and timing of the engine's intake and exhaust systems (partially or entirely), reducing fuel consumption and improving efficiency. Relevant information is as follows: Definition: The variable valve timing system OCV, VCT consists of an electromagnetic valve (OCV) and a variable camshaft phase regulator (VCT). By adjusting the engine camshaft phase, the intake volume can change with engine speed, thereby achieving optimal combustion efficiency and improving fuel economy. Working principle: Piston engines typically intake and exhaust by lifting the throttle valve. The lift valve is driven directly or indirectly by the cam on the camshaft. In each intake and exhaust cycle, the cam drives the valve to open (lift) for a certain time (overlap time).