Exhaust valve for a large sized two stroke diesel engine, process for reduction on nox-formation in such an engine and such engine
AssigneeMan Diesel & Turbo, Filial Af Man Diesel & Turbo SE, Tyskland
InventorMads Lytje Christensen
Life of this patent
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Abstract
For reducing the NOx-emission of a large sized two stroke diesel engine having at least one combustion room (3), a reciprocating piston (4) and an exhaust opening (12) controlled by an exhaust valve (13) at each work cyclus a small volume of burnt gas is retained in the combustion room (3) and so added to the fresh air for the next combustion. For achieving this retention of burnt gas the underside of the valve disc (15) off the exhaust valve (13) is provided with a shallow concave face (17) building a basin-like collection room, whose depth is within a range of 2-10% of the outer diameter of the valve disc (15).
Claims41
Exhaust valve designed for controlling an exhaust opening (12) of a large sized diesel engine of the two stroke type and having a valve disc (15) arranged at the lower end of a valve shaft (14), whereby the valve disc's (15) underside to face a combustion room (3) is provided with a basin designed as a rotationally symmetric cavity (18), being surroundingly bordered and being downwardly open, characterized in that for retention of burnt gas, the maximum of rise of the concavely shaped underside of the valve disc (15) relative to an imaginary planar face (23) directly supporting the valve disc (15), is within the range of 2-10% of the outer diameter of the valve disc (15).
Exhaust valve according to one or more of previous claims, characterized in being identifiable by data contactlessly read from at least one tag of said valve, preferably a tag of a RFID-type, comprising stored data to unambiguously define said valve.
Process for reduction of the NOx-formation in a large sized diesel engine (1) of the two stroke type having at least one combustion room (3) with an exhaust opening (12) coaxially arranged within and controlled by an exhaust valve (13) which is realized according any of the foregoing claims, whereby in the combustion room (3) at each work cycle a fuel injection, a combustion of fuel, an ejection of burnt gas, a scavenging and filling with fresh air as well as a compression of the filling of the combustion room (3) are carried out, whereby some burnt gas is added to the air before combustion, and whereby at least some of the burnt gas added to the air is conserved in the combustion room (3) in the manner of a nest (19) of burnt gas built within the rim area of the underside of the said exhaust valve (13) being concavely shaped on the underside.
Dependencies are inferred from the claim text.