Camshaft structure and position Structure The main body […]
Camshaft structure and position
The main body of the camshaft is a cylindrical rod with approximately the same length as the cylinder group. There are several cams on it, which are used to drive the valve. The camshaft is supported in the camshaft bearing hole through the camshaft journal, so the number of camshaft journals is an important factor affecting the stiffness of the camshaft support. If the camshaft has insufficient rigidity, it will bend and deform during operation, which will affect the timing of the gas distribution.
The side of the cam is egg-shaped. The purpose of its design is to ensure adequate intake and exhaust of the cylinder. In addition, considering the durability of the engine and the smoothness of operation, the valve should not have too much impact due to the acceleration and deceleration process in the opening and closing action, otherwise it will cause severe valve wear, increased noise or other serious consequences. Therefore, the cam has a direct relationship with the engine's power, torque output, and smoothness of operation.
The position of the camshaft has three types: bottom-mounted, middle-mounted and upper-mounted. The camshaft of the lower-mounted air distribution mechanism is located in the crankcase, the camshaft of the middle-mounted air distribution mechanism is located on the upper part of the body, and the camshaft of the upper-mounted air distribution mechanism is located on the cylinder head.
The engines of most production cars are now equipped with overhead camshafts. The main advantages of the overhead camshaft structure are fewer moving parts, short transmission chain, and high rigidity of the whole mechanism, which makes the camshaft closer to the valve and reduces the bottom camshaft caused by the large distance between the camshaft and the valve. The waste of kinetic energy back and forth. Engines with overhead camshafts have faster valve opening and closing actions, so the speed is higher and the running smoothness is better.