What occurs to the piston during the intake stroke?

During the intake stroke of an engine, the piston moves downward within the cylinder. This downward motion creates a vacuum or negative pressure, which pulls in the air-fuel mixture through the open intake valve. The significance of this process lies in how it initiates the internal combustion cycle; as the piston descends, the space inside the cylinder increases, allowing the air-fuel mixture to enter smoothly.

Understanding this movement is crucial, as it sets up the conditions necessary for the subsequent compression stroke when the piston will move back upward to compress the air-fuel mixture before ignition occurs. Therefore, the downward movement of the piston during the intake stroke is a vital component of the engine's operation.