FIELD: engines and pumps.
SUBSTANCE: exhaust valve to adjust exhaust orifice 12 has valve disc 15 arranged nearby lower end of valve stem 14. Valve disc lower side facing combustion chamber 12 has cup made up of rotary symmetric cavity 18 open downward with confined perimetre. To retain combusted gas, maximum of valve disc concave lower side lift with respect to imaginary flat face surface 23 that makes direct support for valve disc 15, varies from 2 to 10% of valve disc OD. Invention covers also NOx reduction procedure, versions of exhaust valve fabrication, versions of large-size diesel engine fabrication, method of large-size diesel engine fabrication, and method of large-size diesel engine alteration.
EFFECT: reduced NOx emission.
41 cl, 4 dwg
