Patent ID: 7476090

Claim:
An Internal combustion engine comprising: an engine structure having an Internal volume including an oil reservoir, wherein an amount of oil is collected in an oil pool in the reservoir; a turbocharger mounted to said engine structure and having a center-housing connected to a turbine housing and a compressor housing; wherein the center-housing includes a bore, a shaft disposed in the bore operatively coupling a turbine wheel inside the turbine housing with a compressor wheel inside the compressor housing, at least one bearing disposed between the shaft and the bore, an oil cavity, an oil supply passage and an oil drain passage, in fluid communication with the oil cavity, and; a vent passage that opens to the oil cavity at a location along an exposed portion of the length of the shaft extending between the bearing and an oil seal that is disposed on the shaft proximate an interface between the center-housing and the turbine housing; an oil pump in fluid communication with the oil supply passage and the oil pool; a vent tube fluidly connecting the vent passage with the internal volume, wherein the vent tube is arranged to equalize pressure of the oil cavity In the center-housing to pressure of the internal volume of the engine structure by communicating with the oil cavity through the vent passage in the center-housing and not through the oil supply and oil passages.