overhead camshaft 1 Introduction
overhead camshaft. (English: Overhead camshaft, referred OHC) is a today’s popular automotive engine valve mechanism. In this configuration, the cam shaft is placed within the cylinder head, a combustion chamber above the direct drive rocker arm, valve, without going through a long putter. Compared to the same number of valve pushrod engine (i.e., overhead valve configuration), overhead camshaft arrangement reciprocating member needs much less, thus greatly simplifying the valve structure, significantly reduce weight of the engine, while also improve the transmission efficiency and reduce operating noise. Although overhead cam engine structure is more complex, but it brings better overall engine performance (in particular, a significant increase in ride comfort) and a more compact engine structure, the engine manufacturers will soon widely application of this design. Driving manner with overhead valve overhead cam configuration is not necessarily different. Power can be transferred to the overhead cam shaft through a timing belt, chain or even gear set.
In addition, overhead camshaft engine structure using this design to achieve higher than the overhead valve engine with a camshaft structure or unitary structure of the rotational speed.
Today, many OHC engines have adopted the structure of multi-valve timing or variable valve structure to improve efficiency and dynamic performance of the engine.
generally in accordance with the number of the camshaft of the valve structure comprises, overhead camshaft can be divided into two forms:
SOHC (Single overhead camshaft, SOHC)
DOHC (Double overhead camshafts, DOHC)