Camshaft action The camshaft is a part of the engine's […]
The camshaft is a part of the engine's valve train, which is responsible for driving the valve to open and close on time, to ensure that the engine regularly inhales fresh combustible gas mixture for the cylinder during operation, and discharges the combusted exhaust gas to the cylinder in time.
Nowadays, automobile engines generally adopt the design of overhead camshafts. According to the number of overhead camshafts, they are divided into single overhead camshafts and double overhead camshafts.
The intake and exhaust valves are combined on a single camshaft, the single overhead camshaft (SOHC).
The intake valve and exhaust valve are arranged on two camshafts, namely the double overhead camshaft (DOHC).
Advantages and disadvantages of camshafts
All the valves of the single overhead camshaft are driven by a camshaft through the top rod, but due to the different positions of the valves in the intake port, the accuracy of the action cannot be maintained, and the effect is slightly worse.
The double overhead camshaft can get better performance, but it needs to be equipped with one more camshaft.
The manufacturing process of Cold shock camshaft blank Manufacturers the double overhead camshaft is complex and the cost is high; the single overhead camshaft has a simple structure and good durability, which can not only meet the dynamic requirements of general customers, but also meet their economic requirements.
The single overhead camshaft uses a single camshaft strip to directly drive the intake and exhaust valves on the cylinder head. It has a simple structure and is suitable for high-speed engines. The side-mounted camshaft generally used in the past, that is, the camshaft is on the side of the cylinder head, and is directly driven by the timing gear. In order to convert the rotation of the camshaft into the reciprocating motion of the valve, a valve lifter must be used to transmit power. In this way, there are many parts in reciprocating motion, and the inertial mass is large, which is not conducive to the high-speed motion of the engine. Moreover, the slender tappet has a certain elasticity, which is easy to cause vibration, accelerate the wear of parts, and even make the valve out of control. Overhead twin camshafts are two camshafts mounted on the cylinder head, one for driving the intake valve and the other for driving the exhaust valve. The use of double overhead camshafts does not require high design requirements for camshafts and valve springs. It is especially suitable for hemispherical combustion chambers with V-shaped valves, and is also easy to use with four-valve valve trains. Under the same working volume, the gas distribution of the DOHC is more accurate, and the fuel utilization rate is also higher. But the maintenance is relatively complicated, but now it is not much different from the single overhead.
The advantage of maintaining a naturally aspirated is that when driving continuously and intensely, the heat generation is smaller than that of the supercharger, and the heat penetration and heat attenuation of the engine and its accessories are less affected. Therefore, the naturally aspirated engine is caused by the air heating in hot weather. The performance drop is also much smaller than that of the supercharged system; at the same time, the naturally aspirated method does not need to add as many additional accessories (supercharger, pipeline, radiator, etc.) as the supercharger, and has more advantages in weight; Some brands of twin-screw supercharging kits are used as an example. After the supercharging kits are installed, the weight may increase by about 40kg compared with the natural aspirated ones; and the extra weight of the mechanical supercharging system basically acts on the front wheels, which is very important for the front and rear parts of the body. The weight ratio has a greater impact, which will affect the handling on the track, as well as the center of gravity transfer effect to be achieved when running a straight start and ejecting. The disadvantage of the naturally aspirated system is the torque in the low-speed range, which is why the naturally aspirated prefers to increase the speed, especially after upgrading the camshaft and full exhaust, there are probably few noises that erupt at high speeds. Men can resist that charm.