Patent ID: 8387243

Claim:
A method of manufacturing a multistage exhaust turbocharger for an internal combustion engine, the multistage exhaust turbocharger including a high-pressure stage turbocharger having a high-pressure turbine drivable by exhaust gas from an exhaust manifold of the engine, and a low-pressure stage turbocharger having a low-pressure turbine drivable by exhaust gas flowed out from the high-pressure turbine after driving the high-pressure turbine, said method comprising: providing a high-pressure turbine housing of the high-pressure stage turbocharger, the high-pressure turbine housing being integrally formed with the exhaust manifold by casting; assembling constituent parts of the high-pressure stage turbocharger using the high-pressure turbine housing as a reference; after said assembling constituent parts of the high-pressure stage turbocharger, attaching the low-pressure stage turbocharger to the high-pressure stage turbocharger by attaching a low-pressure turbine housing to a low-pressure turbine connection flange provided at an exhaust outlet side of the high-pressure stage turbocharger; and after said attaching the low-pressure stage turbocharger, attaching an air supply channel to connect between a supply air outlet of the low-pressure stage turbocharger and a supply air inlet of the high-pressure stage turbocharger, wherein the high-pressure stage turbocharger has a rotation axis, wherein the low-pressure stage turbocharger is disposed below the high-pressure stage turbocharger when viewed in a direction parallel to the rotation axis of the high-pressure stage turbocharger, wherein the high-pressure stage turbocharger and the low-pressure stage turbocharger are arranged sequentially in the flow path of the exhaust gas of the engine, wherein the high-pressure stage turbocharger has a high-pressure compressor and the low-pressure stage turbocharger has a low-pressure compressor, and wherein the air supply channel supplies supply air for the engine pressurized by the low-pressure compressor to the high-pressure compressor to be further pressurized by the high-pressure compressor.