intake- and exhaust valves seal the combustion chamber and regulate the charge exchange process. Valves are thermally and mechanically highly stressed parts which are also exposed to corrosive influences.
the mechanical stress is caused by the bending of the valve head under ignition pressure and by heavy impact during closure (shock load). These stresses can be infl uenced and controlled by designing the valve head with appropriate strength and shape. When open, during the exhaust stroke, the exhaust valve is also heated by the escaping hot exhaust gases.
intake- and exhaust valves
valve cooling takes place mainly by heat conduction via the valve seat into the cylinder head. Much less heat is conducted into the head via the valve guides. Intake valves reach temperatures of approx. 300 °c to 550 °c, whereas exhaust valves can get as hot as 1,000 °c.