Patent ID: 8353158

Claim:
A turbocharger comprising: a turbocharger shaft for rotation about an axis and for supporting a compressor wheel at first end and a turbine wheel at a second end; a bearing housing having a wall defining a bore in which the turbocharger shaft is received with a substantially annular clearance, the turbocharger shaft being supported for rotation in the bore by at least two journal bearings housed within the annular clearance; a first gas seal between the turbocharger and the bearing housing proximate the first end of the turbocharger shaft; a second gas seal between the turbocharger shaft and the bearing housing proximate the second end of the turbocharger shaft; at least one fluid passage for delivering lubricating fluid from a fluid source to the at least two journal bearings; at least three fluid retaining members, including a first, a second, and a third fluid retaining member, disposed around the turbocharger shaft and each having an outer portion that is sealed to the wall, and each disposed between the first and second gas seals; and the at least two journal bearings being disposed at an axial position between the first fluid retaining member and the second fluid retaining member and the third fluid retaining member being disposed between a first journal bearing and second journal bearing of the at least two journal bearings so that, in use when the turbocharger shaft is not rotating, a volume of lubricating fluid is retained in a first lubricating fluid reservoir defined between the first and third fluid retaining members and the wall to a depth that at least partially immerses the first journal bearing, and in a second lubricating fluid reservoir defined between the second and third fluid retaining members and the wall to a depth that at least partially immerses the second journal bearing.