The valve stem reciprocates up and down in the valve guide, and is subjected to periodic impacts, which requires a certain degree of matching accuracy and wear resistance. The valve spring ensures that the valve is correctly reset and prevents the valve from breaking the seal due to bouncing when the engine vibrates. The valve guide plays a guiding role, ensuring the correct matching and opening and closing between the valve and the valve seat. The valve seat and the valve head seal the cylinder, and at the same time receive the heat from the valve head, playing a role in cooling the valve.
