What is the difference between single top and double top of automobile valve structure? Be specific, please.

At present, the common valve structures are divided into single overhead camshaft (SOHC) and DOHC.

Single overhead camshaft (SOHC) means that there is only one overhead camshaft on the cylinder block, which drives the intake valve and exhaust valve at the same time. DOHC means that there are two overhead camshafts on the cylinder block, the first one drives the intake valve and the second one drives the exhaust valve.

Single camshaft has simple mechanical structure, few problems and large low-speed torque. The opening time of the intake valve and exhaust valve of a single camshaft is fixed, but the advantages of simple mechanical structure, convenient maintenance, economy and fuel saving are all single convex. Because the double camshafts can change the overlapping angle of the valves, they can exert relatively large horsepower, but the torque is insufficient at low speed, and it will also cause certain maintenance difficulties because of the complicated mechanical structure. The technology of double camshaft comes from racing car, which can mainly control the time difference between intake valve and exhaust valve.

Monoconvex and biconvex are not absolutely good or bad, but have different structures. As can be seen from the above, SOHC has advantages in torsion and fuel consumption, so it is more suitable for urban driving, and DOHC has advantages in horsepower, so it is more suitable for high-speed driving.