How to exhaust the exhaust valve?

The exhaust process of the exhaust valve is as follows: 1. Exhaust can be divided into two stages. In the first stage, the exhaust valve is opened before the piston descends to the bottom dead center. At this time, the in-cylinder pressure is about 4kg u002F cm2 (when the carburetor throttle is fully open), which is much higher than the atmospheric pressure. At this time, the exhaust gas rushes out at its own pressure, because the rushing out speed is extremely fast (about 400-500m u002F seconds) and the noise is very high. 2. In the second stage, the piston pushes the exhaust gas, and the piston moves upward from the bottom dead center to discharge the exhaust gas. After the piston passes the top dead center, the exhaust cabinet is still not closed, because at this time, the exhaust gas still flows out inertia and can continue to be discharged. After the piston begins to descend for a period of time (equivalent to crankshaft rotation 10-200) after passing the top dead center, the exhaust valve closes and the exhaust stops. Therefore, the beginning and end of the upward movement of the piston is the stage when the piston pushes and exhausts.