In a four-stroke engine, the intake valve opens in the intake stroke, allowing air-fuel mixture to enter, while the exhaust valve remains closed. During the compression stroke, both valves stay closed to build pressure. In the power stroke, the fuel ignites, pushing the piston down, with both valves still closed to retain pressure. Finally, in the exhaust stroke, the exhaust valve opens, allowing gases to escape, while the intake valve stays shut. This cycle repeats continuously, ensuring efficient engine operation.
In a four-stroke engine, both the intake and exhaust valves are closed during the power stroke, allowing for maximum pressure to build from the combustion of the air-fuel mixture. Similarly, during the exhaust stroke, both valves are also closed momentarily after the power stroke until the piston moves up to expel the exhaust gases. However, the intake valve opens before the power stroke begins, and the exhaust valve opens at the end of the power stroke to facilitate the exhaust process. Thus, while both valves are closed during the power and exhaust strokes themselves, they open at specific times in the cycle.
Is the time when intake and exhaust valve remain oper during the exhaust stroke.
Is the time when intake and exhaust valve remain oper during the exhaust stroke.
600 rpm / 60 = 10 revs per second. The intake valve opens on every other revolution (2 revolutions for every four-stroke cycle). This results in 5 intake valve openings per second!
While there may be some overlap of valve opening timing, generally speaking, the exhaust valve opens after the power stroke, and the intake valve opens after the exhaust stroke. Recap... We start the combustion cycle of a standard 4-stroke engine with the intake stroke, the intake valve is open and the vacuum created by the downward movement of the piston draws in the air/fuel mixture from the intake manifold. The intake valve closes as the piston rounds bottom dead center and the compression stroke begins on the upward movement of the piston. At or near the top of the compression stroke, the spark plug fires (both valves are closed at this point) and begins the downward power stroke. As the piston rounds bottom dead center again, the exhaust valve opens to allow the piston to push out the exhaust gasses during the upward exhaust stroke. As the piston gets to the top, the exhaust valve closes and the intake valve opens to start the process over again.
The purpose of butter fly valve is to maintain one way opening during induction stroke and exhaust stroke.
The term for the time when both the intake and exhaust valves are open simultaneously is called "valve overlap." This occurs during the end of the exhaust stroke and the beginning of the intake stroke in a four-stroke engine cycle. Valve overlap can enhance engine efficiency by allowing better exhaust scavenging and improved intake charge filling.
Is the time when intake and exhaust valve remain oper during the exhaust stroke.
AV valves close during the systole phase of the cardiac cycle.
If im not mistaken, during the power stage the intake and exhaust valves are both closed. the intake valve opens pulling air into the cylinder (cycle one) and the exhaust valve opens (cycle 4) to relase the air fuel mix that was ignited.
valve timing diagram of two stroke engine