What is the function of engine valve timing?
2 Answers
Engine valve timing mechanism serves to: timely open and close the intake and exhaust valves of each cylinder, allowing fresh combustible mixture (for gasoline engines) or air (for diesel engines) to enter the cylinder promptly, and exhaust gases to be expelled from the cylinder in a timely manner. Below is a partial introduction about engines: 1. Definition: An engine is a machine capable of converting other forms of energy into mechanical energy. 2. Classification: Internal combustion engines, external combustion engines (such as Stirling engines, steam engines, etc.), jet engines, electric motors, etc. 3. Composition: The engine block assembly mainly consists of components such as the cylinder block, cylinder liner, cylinder head, and cylinder gasket.
Engine valve timing, simply put, is the precise control of when the valves open and close, which directly affects the amount of air intake. For example, when I often tinker with old cars, I find that if the timing is set incorrectly—if the intake valve opens too late or closes too early—air can't get in or exhaust can't be fully expelled, leading to incomplete combustion of gasoline in the cylinders. This immediately results in a weak engine with sluggish acceleration. At higher RPMs, less air and more residual exhaust gases remain, causing fuel consumption to spike and black smoke to pollute the environment. Modern cars now come equipped with variable valve timing systems that automatically adjust the valve opening and closing points based on RPM. For instance, when overtaking, the intake valve opens wider and earlier to allow more air, delivering stronger torque. In city driving, the system tightens up to save fuel, making the engine breathe more smoothly and efficiently while reducing issues. Regularly checking the timing belt or chain to ensure it doesn't slip can extend the engine's lifespan.
