What are the main components of the valve train?
2 Answers
The valve train mainly consists of two parts: the valve group and the valve transmission group. The valve group includes components such as the valve, valve guide, valve seat, valve lock, and valve spring. The valve transmission group includes the camshaft, timing gear (or timing chain and sprocket, timing belt), tappet (push rod), rocker arm, rocker arm shaft, rocker arm bracket, and timing chain tensioner. The engine valve train operates according to the working cycle and ignition sequence requirements of each cylinder in the engine, timing the opening and closing of the intake and exhaust valves for each cylinder. This allows fresh combustible mixture or air to enter the cylinder immediately and exhaust gases to be expelled from the cylinder. During the compression and power strokes, the valve train closes the valves to ensure the combustion chamber remains sealed. The main parameters and forms of the valve train components are designed to minimize intake and exhaust resistance. The timing and duration of the intake and exhaust valve openings are optimized to ensure relatively sufficient intake and exhaust, resulting in higher power torque and better emission performance. The degree to which fresh mixture or air fills the cylinder is represented by the volumetric efficiency. Higher volumetric efficiency indicates that more fresh air or combustible mixture enters the cylinder, increasing the potential heat generated by the combustion mixture and thus the engine's power. For an engine of a given displacement (V), the mass of the intake charge is related to the final intake temperature (T) and pressure (P). Lower intake T and P result in greater intake mass and higher volumetric efficiency.
The valve train mainly consists of core components such as the camshaft, valves, valve springs, and rocker arms. The camshaft serves as the control center, driving the cams through rotation to open and close the valves. The valves are responsible for opening and closing the intake and exhaust passages, while the springs ensure timely valve closure to prevent gas leakage. The rocker arms or pushrods connect the camshaft to the valves, transmitting motion force. Having worked on many cars, I've found that the material of these components significantly impacts performance. For example, aluminum alloy cams are lightweight, improving response speed, but they wear more easily and require regular lubrication and inspection. Carbon buildup on the valve seats is a common issue, leading to reduced power. Timely cleaning can prevent engine shaking or increased fuel consumption. Ensuring the efficient operation of the valve train is crucial for engine performance. During daily driving, avoid frequent hard acceleration.
