1. Oil Flow in Gasoline Engines Christopher Hammond, John Lindsay Smith, Moray Stark, David Waddington Department of Chemistry: University of York Richard Gamble, Martin Priest, Christopher Taylor School of Mechanical Engineering: University of Leeds Harold Gillespie, Eiji Nagatomi, Ian Taylor Shell Global Solutions (UK)

2. Introduction Aim To Predict Increase in Piston Friction with Oil Degradation Chemical Model for Base Fluid Oxidation Rheological Model for Increase in Viscosity Tribological Model for Piston Friction In This Talk Measure Fluid Flow in Piston Ring Pack Comparison with Tribological Model Chemical Model using Measured Flow Parameters

3. Engine Specification Ricardo Hydra Fuel Injected Gasoline Single Cylinder 0.5 litre Capacity 1500 rpm 50% Throttle External Sump (70 ºC) Camshaft Lubricated Separately Shell XHVI ™ 8.2 No Additive Package Lubricant Specification

4. Extraction of Oil from Top Piston Ring 1/8” PTFE Tube Sample Collection

5. Piston Assembly

6. Oil Flow in Engine Sump Ring Pack Small Volume Short Residence Time Large Volume Long Residence Time Flow Rate

7. Ring Pack Residence Time : ringpack 1-e -1

8. Ring Pack Residence Time : 60 sec

9. Ring Pack Residence Time – Previous Work S B Saville, F D Gainey, S D Cupples, M F Fox, D J Picken, SAE Technical Paper, International Fuels and Lubricants Meeting, Oct 10-13, 1988

10. Oil Flow and Chemistry in Engine Sump Ring Pack High Temperature Small Volume Short Residence Time Low Temperature Large Volume Long Residence Time

11. Oxidation Chemistry Infrared Spectroscopy of Carbonyl Group Hydrocarbon Base Fluid Hydroperoxides Ketones CarboxylicAcids

12. Oxidation in Sump – IR Spectrospcopy

13. Oxidation in Ring Pack

14. Oxidation in Ring Pack : Previous Work S B Saville, F D Gainey, S D Cupples, M F Fox, D J Picken, SAE Technical Paper, International Fuels and Lubricants Meeting, Oct 10-13, 1988

15. Sump Residence Time and Oil Flow Rates

16. Characterisation of Ricardo Hydra Engine Ring Pack Residence Time60 ± 15 seconds Volume of Oil0.30 ± 0.08 cm 3 Temperature200 °C Flow Rates Into Ring Pack0.32 ± 0.02 cm 3 min -1 Returning to Sump0.27 ± 0.01 cm 3 min -1 Loss From Ring Pack0.05 cm 3 min -1 Sump Residence Time156 ± 8 hours Volume3 litres Temperature70 °C Conditions: 1500 rpm, 50% Throttle

17. Piston Assembly

18. Comparison with Tribological Model Ring PackExperiment Theory Residence Time60 ± 15  10 seconds Volume of Oil0.30 ± 0.08  0.02 cm 3 Flow Rates Into Ring Pack0.32 ± 0.02  0.17 cm 3 min -1 Returning to Sump0.27 ± 0.01  0.12 cm 3 min -1 Loss From Ring Pack0.05  0.05 cm 3 min -1 Sump Residence Time156 ± 8  300 hours Conditions: 1500 rpm, 50% Throttle

19. Oxidation Chemistry Hydrocarbon Base Fluid Hydroperoxides Ketones CarboxylicAcids DiketonesHydroxyketones Current Mechanism

20. Two Reactor Simulation Residence Time VolumeTemperature Sump 156 hours 3 litre 70 C Ring Pack 60 sec 0.27 cm 3 200 C

21. Conclusions Measured Oil Flow in Gasoline Engine Modelled Fluid Flow in Ring Pack Modelled Base Fluid Oxidation in Engine

22. Abstract for STLE Houston 2002 Conference: The Interaction of Lubricant Degradation and Tribology in Automotive Gasoline Engines Harold Gillespie, Eiji Nagatomi, Ian Taylor, Shell Global Solutions, Shell Research Ltd, PO Box 1, Chester, CH1 3SH, UK Richard Gamble, Martin Priest, Christopher Taylor School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT, UK Christopher Hammond, John Lindsay Smith, Moray Stark, David Waddington Department of Chemistry, University of York, York YO10 5DD, UK This work aims is to develop a good understanding of lubricant base fluid degradation in automotive gasoline engines and how this affects engine tribology. Therefore an integrated model has been developed that describes both the lubricant flow within the piston assembly and the chemical degradation of the lubricant. Experiments with a Ricardo Hydra gasoline engine have been performed using only a hydrocarbon base fluid as lubricant, with no additive package. Oil extraction from the ring pack has allowed the residence time of oil in the ring pack and the flow rate of oil from the sump to the ring pack to be determined; these are compared with oil transport models. The rate of oxidation of the base fluid has been determined by FTIR spectroscopy; the rate of base fluid oxidation compares well with simulations using a chemical model based on detailed free radical chemistry. Biography: The author is a research chemist with a background in studying chemical kinetics. Previous topics of investigation have been in the field of hydrocarbon combustion and process development in chemical engineering. This background is now being used to study the breakdown of lubricants in gasoline engines.