What type of valves are primarily used for intake and exhaust in engines?

Intake and exhaust in engines are primarily operated by poppet type valves, which are designed to open and close at precise times during the engine's cycle. Poppet valves consist of a cylindrical head mounted on a shaft, and they open by moving upward or downward to allow air-fuel mixture to enter the combustion chamber or exhaust gases to exit. Their straightforward design and reliable sealing capabilities make them highly effective for managing the flow of gases in internal combustion engines.

Other types of valves, such as rotary valves, butterfly valves, and check valves, serve different purposes. Rotary valves, for example, are often used in applications requiring a less direct flow path and are more common in certain types of mechanical systems rather than in conventional automobile engines. Butterfly valves are primarily utilized in larger systems for regulating flow and are not suitable for the high-speed operation and sealing requirements of engine intake and exhaust. Check valves are designed to allow flow in one direction and prevent backflow, making them ideal for various piping systems but not for controlling intake and exhaust cycles in engines. Thus, the design and functionality of poppet valves make them the primary choice for engine applications.