mechanism is an intake valve, an exhaust duct of the control mechanism, which requires working order in accordance with the cylinder and the working process, time opening and closing intake and exhaust valves, the combustible gas mixture (petrol engine) or fresh air is supplied to the cylinders (diesel) and exhaust emissions in a timely manner. Further, when the intake and exhaust valves closed, to ensure the seal cylinder. Composition
1. Valve mechanism
are used in general automotive engine valve type valve train, the valve-type valve and the valve train mechanism is mainly composed valve train group consisting.
valve train includes a valve, valve guides, valve seat and valve spring and other parts, and some of the intake valve also has a valve rotation mechanism, the valve of the cylinder group should ensure that the valve seal.
Transmission gate valve group including a camshaft timing gears, and catheter tappet push rod, rocker arm and rocker shaft, its role is the phase of the intake and exhaust valve by a predetermined their time for opening and closing, and to ensure there is enough opening.
2. Classification valve means
Depending on the mounting position of the valve mechanism into the valve OHV-type valve means and valve side-mounted valve means .
is located in the cylinder head valve the valve called an overhead valve gear, cam, tappet push rod, rocker arm, valve and valve springs and other components. Characterized in intake resistance is small, compact combustion chamber structure, large airflow agitator, can achieve high compression ratios, are currently made automobile engine valve using an overhead valve train.
side surface of the valve body of the cylinder valve called side-mounted valve gear, cam, tappet, valve and valve springs and other components. Eliminating the push rod, rocker arms other member, the structure is simplified. Because of its intake and exhaust valves on one side of the cylinder, the compression ratio is restricted, greater resistance to intake and exhaust valves, power and high speed engines are poor, gradually be eliminated.
3. The overhead camshaft valve train
Camshaft mounting position of the
has a generally underlying engine, center, overhead three forms. Overhead camshaft is a camshaft placed in the cylinder head above the combustion chamber, to directly drive the rocker arm, a valve, without going through a long putter.
compared to
in the same number of valve pushrod engine (i.e., overhead valve configuration), overhead camshaft arrangement requires reciprocation much less, thus greatly simplifying the valve structure, significant reduce the weight of the engine, but also improve the transmission efficiency and reduce operating noise.
according to the number of the camshaft within the valve structure comprises, overhead camshaft can be divided into two forms:
SOHC (Single overhead camshaft, SOHC)
DOHC (double overhead camshafts, DOHC)