Abstract

Emission regulation standards have become so stringent that the use of after-treatment devices with I.C. engines is necessary in many markets. Engine lubricants have been reported to reduce the effectiveness of these after-treatment devices while also contributing to hydrocarbon and particulate emissions. Oil consumption measurement has thus become of increasing interest. In this paper, oil emission measurement is conducted using the direct mass spectrometry measurement of oil derived (high mass) hydrocarbons in an SI engine exhaust stream. Oil and fuel compounds are separated with a quadrupole mass filter thus enabling fast response measurement. Low sensitivity at high hydrocarbon mass numbers requires the mass spectrometer to utilize a special high pass mode to obtain sufficient sensitivity. Even though the relationship between oil consumption and exhaust bourne oil derived compounds is uncertain owing to the partial combustion and fragmentation of oil during the combustion event, such measurements yield complex and important information about the concentration of unburnt oil components in the exhaust. Results are presented from a conventional 4 cylinder PFI engine as a function of speed and load on a simulated NEDC cycle. The results provide some support for previous measurements though there are also significant differences.