Chapter 3 Ventilation system Section 1 Valve train The function of valve train in accordance with the work process and the requirements of the order of fire of every engine cylinder,open and close the intake and exhaust valves of each cylinder in time,supply clean,adequate amount of fresh air or combustible mixture on time,and discharge emissions as thoroughly as possible in time,in order to ensure effective combustion process. 机械电子工程学 Automobile and Tractor Northwest A&F University Automobile and Tractor Northwest A&F University Chapter 3 Ventilation system The function of valve train in accordance with the work process and the requirements of the order of fire of every engine cylinder , open and close the intake and exhaust valves of each cylinder in time, supply clean, adequate amount of fresh air or combustible mixture on time, and discharge emissions as thoroughly as possible in time, in order to ensure effective combustion process. Section 1 Valve train