What does i-VTEC, the unique technology of Accord engine, mean in vernacular?

I have a video here, which I believe will be easier to understand than words /v_5_ 1459.html, or you can search the principle of i-VTEC technology. First of all, you have to know the concepts of valve, valve lift and valve timing, which should be better understood. VTEC technology: The main difference between VTEC engine and general four-valve engine lies in intake rocker arm and intake camshaft. At this time, the lift of one valve is very small, and it hardly participates in the intake process. The intake port is basically equivalent to a two-valve engine. However, because the flow direction of intake air does not pass through the center of the cylinder, a strong intake vortex can be generated, which can improve the uniformity of the mixture, increase the combustion rate, reduce the wall chilling effect and the influence of clearance at low speed, especially under the condition of cold car, and make the combustion more complete, thus improving the economy and greatly reducing the emission of HC and CO. At high speed, the VTEC solenoid valve controls the direction of pressure oil, so that the two intake rocker arms are connected into a whole, from the one with the longest opening time and the largest lift. At this time, the two intake valves are synchronized according to the contour of the large cam. Compared with low-speed operation, it greatly increases the intake flow area and opening duration, thus improving the dynamic performance of the engine at high speed. I-VTEC technology: Compared with VTEC system, I-VTEC system adds VTC mechanism to VTEC system, that is, i-VTEC=VTEC+VTC. In order to obtain the most suitable valve timing under working conditions, ECU controls the load of VTC oil pressure control valve and provides oil pressure to intake advance angle oil pressure chamber or intake retard angle oil pressure chamber in VTC actuator. VTC actuator changes the phase of camshaft according to the supplied oil pressure, so as to obtain the best under this load.