What is the primary function of the valves in an engine?

The primary function of the valves in an engine is to allow the air-fuel mixture to enter the combustion chamber during the intake stroke and to facilitate the expulsion of exhaust gases after combustion during the exhaust stroke. This process is essential for the operation of a four-stroke combustion engine, consisting of intake, compression, power, and exhaust cycles.

During the intake stroke, the intake valves open, allowing the pre-mixed air and fuel to enter the combustion chamber. Following the combustion process, the exhaust valves open to release the spent gases, enabling the cycle to start anew. This cyclical opening and closing of the valves is crucial to maintain proper engine performance and efficiency.

Thus, the central role of the valves is to manage the flow of air and fuel into and out of the combustion space, directly impacting the engine's efficiency and power output.