Analysis of the power loss reduction in automotive turbo-charger systems with independent lubrication 2018-36-0302
A typical turbocharger has in its interior an shaft that supported by two bearings, which are normally hydrodynamically lubricated, that is, the friction reduction between the metal parts takes place through the formation of a lubricating oil film. This lubricating oil film may reduce friction about to a thousand times; however, since it is a liquid, there is a resistance to the shaft movement proportional to the oil viscosity. In the case of a turbocharger coupled to an internal combustion engine, it has the purpose of increasing the power produced by the engine itself; therefore, this resistive force must be as small as possible, so that the system efficiency may increase, as well as the power output. A turbocharger-engine system uses the same lubrication system, where the lubricating oil must have characteristics that meet the engine requirement, where the operating conditions are more stringent. However, the lubricating oil of the turbocharger should only be resistant to the same working temperature of the engine environment, allowing the use of a less viscous lubricant. The present work analyzes an application of independent lubrication system, exclusive to the turbocharger, where a less viscous lubricating fluid can be used. For this case, a study was carried out from the appropriate selection of the components and the computational modeling of the system for performance analysis. It has been observed that, using a suitable lubricant for the turbocharger bearings independently from the engine lubrication system, a reduction in power loss of 55% is achieved. Therefore, the power supply for the internal combustion engine may be increased, resulting in a higher system performance.