Exhaust turbocharger for internal combustion engine and turbocharging system

摘要

A turbine impeller to be driven for rotation by exhaust gas of an internal combustion engine is fixed to a turbine shaft. The turbine shaft is supported by a radial bearing in radial directions and mounted to a bearing housing. The turbine shaft includes a stepped part which is formed between the turbine impeller and the radial bearing so that the outer diameter of the turbine shaft is greater at the turbine impeller side than at the radial bearing side. The bearing housing includes an oil drain for discharging oil which has lubricated the radial bearing. The distance L from a side face of the radial bearing to the stepped part is set to a value at which oil moving from an end of the radial bearing does not reach the stepped part when a turbine-revolution speed Nt is higher than that Nti which is produced by an idling operation of the internal combustion engine.