4.5.5.a Іnlet valve
The inlet valve starts opening a little earlier than the piston comes to TDC. In this case the valve will already open slightly by the beginning of the downward stroke of the piston during the intake stroke. The intake valve opening advance for engines of different models fluctuates in different ranges. Often, the closing of the intake valve occurs with a certain delay when the piston goes over BDC and starts to move up. In this case, for some time after the transition over the BDC, despite the beginning of a slight upward movement of the piston, filling the cylinder with a charge will continue due to some rarefaction still present in the cylinder, as well as due to the inertia of the charge moving in the intake manifold.
Note
However, it should be mentioned that there are at least two cycles that are called Miller and Atkinson cycles, during which the intake valve does not close in the same way as on conventional internal combustion engines.
Thus, the opening time of the intake valve is longer than the time during which a half revolution of the crankshaft occurs. The duration of the intake increases, and the cylinder is more fully filled with a fresh charge.
2 MB