What is the function of the valve train?
3 Answers
The function of the valve train is to open and close the intake and exhaust valves of each cylinder at the right time, allowing fresh combustible mixture or air to enter the cylinder promptly and exhaust gases to be expelled from the cylinder in a timely manner. During the compression and power strokes, it ensures the sealing of the combustion chamber by closing the valves. Below is an introduction to the valve train: 1. The valve train is the mechanism that controls the intake and exhaust of the engine. It regulates the intake and exhaust of the combustion chamber according to the working cycle and ignition sequence of each cylinder, including the intake volume, intake timing, and exhaust timing, thereby adjusting and organizing combustion based on these conditions. 2. Components of the valve train: The valve train consists of two groups—the valve drive group and the valve group. The valve drive group includes the crankshaft timing gear, camshaft timing gear, camshaft, tappet, pushrod, rocker arm, valve clearance adjustment screw and lock nut, and rocker arm shaft. The valve group includes the valve, valve guide, valve spring, valve spring seat, valve oil seal, and valve seat, among others.
Having driven for many years, I truly appreciate the importance of the valve train system in an engine—it controls the opening and closing of those valves. Valves act like small gates: the intake valves open to let the fresh air-fuel mixture into the cylinder, while the exhaust valves open to expel the burned gases. This mechanism ensures the engine runs efficiently, delivering strong power, better fuel economy, and reduced emissions. I remember an old car I once had—when the valve train malfunctioned, it shook violently at idle. After inspection, it turned out a valve was stuck, and once fixed, the engine immediately ran smoothly and quietly. Modern cars now feature smarter valve train systems, some even adjusting valve timing automatically to adapt to different speeds, making the drive even smoother. In short, the condition of the valve train directly impacts engine longevity. I always remind my friends not to overlook it during maintenance—regularly check valve clearance and the camshaft.
As someone who often tinkers with my car, I understand that the valve train is the engine's respiratory system. It uses the camshaft to push the valves open and closed, controlling the timing of intake and exhaust. Simply put, during the intake stroke, the intake valve opens, and during the exhaust stroke, the exhaust valve opens, ensuring that gases enter and exit the cylinder at the right time. If this goes awry—for example, if the valve opens too early or closes too late—the engine's power drops, noise increases, and fuel consumption rises. I once adjusted the valve clearance, and after that, the car's acceleration response improved significantly. Some advanced systems, like VVT (Variable Valve Timing), can automatically optimize based on RPM, being gentler at low speeds in the city and more powerful at high speeds.
