What is the purpose of the valve train?
2 Answers
The purpose of the valve train is: according to the working cycle and firing order requirements of each cylinder in the engine, to timely open and close the intake and exhaust valves of each cylinder, allowing fresh charge to enter the cylinder promptly and exhaust gases to be expelled from the cylinder in a timely manner. During the compression and expansion strokes, it ensures the sealing of the combustion chamber. Based on the different installation positions of the valves, the valve train can be divided into overhead valve train and side valve train. Its principle is to open and close the intake and exhaust valves of each cylinder in accordance with the working cycle and ignition order requirements of each engine cylinder, drawing fresh air into the cylinder and expelling the exhaust gases after combustion from the cylinder.
The valve train plays a crucial role in the engine, primarily controlling the opening and closing of valves to manage the intake of air and fuel as well as the exhaust of combustion gases. Simply put, when the engine operates, it needs to draw in fresh air mixed with fuel and then expel the exhaust gases after combustion. The entire cycle, much like breathing, relies entirely on the valve train for coordination. It involves the camshaft pushing the rocker arms, valve springs ensuring a tight seal when closed, and the timing chain maintaining precise rhythm. If any issues arise here—such as carbon buildup on the valves or misaligned timing—the engine may experience "breathing" difficulties, leading to sudden power loss or a spike in fuel consumption. In my experience, many vehicle malfunctions stem from poor maintenance of this system, like neglecting oil changes, which leads to insufficient lubrication and causes valve sticking or increased noise. Regularly checking valve clearance and cleaning the system can extend engine life and avoid costly overhauls. On the road, a smooth valve train ensures responsive throttle input and seamless high-speed performance without hesitation.
