Patent ID: 8459022

Claim:
A method comprising: providing a controller and a turbocharger assembly that comprises a compressor and an exhaust turbine to extract energy from exhaust of an internal combustion engine and thereby provide energy via the compressor to intake air to increase performance of the internal combustion engine, wherein the exhaust turbine comprises: a housing that comprises: an exhaust volute chamber, a wastegate chamber, a passage that comprises a wastegate opening configured for flow of exhaust from the exhaust volute chamber to the wastegate chamber, a wastegate seat defined by a surface surrounding the wastegate opening, and a bore; and a mono-block arm and plug for closing the wastegate opening wherein the mono-block arm and plug comprises: an arm portion that comprises a free end configured for receipt by the bore of the housing, a plug end and a shaft portion therebetween having a rotational axis z a , and a plug portion extending from the arm portion; wherein the plug portion comprises an outer edge at an outer radius r p , a face and a ridge that comprises a cross-section, the ridge extending outwardly from the face at a radius r r defined from a point on the face and defined by a radial thickness Δr r and a height Δz r extending outwardly from the face, wherein a surface of the plug portion extends a radial distance Δr s from the ridge to the outer edge the plug portion; and wherein the cross-section is configured to change shape responsive to application of force associated with closing the wastegate opening to enhance sealing of the wastegate opening; performing a closing operation via the controller to change shape of the ridge by rotating the shaft portion in the bore of the housing to force the ridge against the wastegate seat to enhance sealing of the wastegate opening by the plug portion; and calling for opening or closing of the wastegate opening via the controller responsive to one or more engine operating conditions wherein opening allows for flow of exhaust from the exhaust volute chamber to the wastegate chamber to reduce extraction of energy from exhaust by the exhaust turbine.