DIESEL PARTICULATE FILTER REGENERATION STRATEGY AND ITS INFLUENCE ON ENGINE OIL CHARACTERISTICS

1. L. Di Stefano, A. Dotta, G. Natoli, G. Pometto, P. Salino M. Fucale, A. Pari DIESEL PARTICULATE FILTER REGENERATION STRATEGY AND ITS INFLUENCE ON ENGINE OIL CHARACTERISTICS Moscow – 28,29 november 2007

2. Contents: • Scenario and objective of the activity • Testing activity • Results • Conclusions Moscow 2007

3. EURO 1 EURO 2 EURO 3 EURO 4 To meet the stringent limit for the emission of particulate matter (PM) set by Euro 4 regulations, Diesel Particulate Filters (DPF) have been developed for applications on Diesel Engines of Passenger Cars. Moscow 2007

4. Diesel Particulate Filters must be periodically regenerated to remove the solid particulate matter accumulated with mileage. Today the most widely adopted regeneration strategy is based on supplementary injections of fuel in order to reach the temperature needed to burn the particulate accumulated in the filter (approximately 600°C). Moscow 2007

5. REGENERATION STRATEGY Injector This quantity will burn inside the exhaust manifold T/C Air inlet Pre Kat Front Kat DPF Moscow 2007

6. Several running parameters are recorded and processed by the Electronic Control Unit to determine the level of soot accumulation and activate regeneration whenever a pre-set value of soot is reached. The rate of soot accumulation in the filter, and therefore the frequency of regeneration, is strictly dependent on driving conditions (urban, highway, combined). To guarantee the protection of the whole system from failure, the temperature and the delta pressure between the filter ends are also constantly monitored. Moscow 2007

7. During the regeneration process, as a consequence of post injections, small fractions of fuel leak in the sump through cylinder liner, mixing with the oil. The objective of the activity was to evaluate the impact of the resulting oil viscosity decrease on engine protection against wear, particularly of those mechanical couplings (shaft/bearings, cam/tappets) whose protection is highly dependent on oil film formation and stability. To this purpose, different running conditions have been simulated in the lab, both on engine on test dynos and directly on a vehicle on the roller dyno. Results have been compared with data generated in a field test. Moscow 2007

8. Characteristic Method Unit Typical value Kv 100°C ASTM D445 mm2/s 15.3 Kv 40°C ASTM D445 mm2/s 90.5 HTHS CEC L 36 A 97 mPa.s 3.7 Total Base Number ASTM D2896 mgKOH/g 9.6 Sulphated Ash ASTM D874 % 1.1 The oil used in the tests is a SAE 5W40, ACEA B3/B4, synthetic formulation Moscow 2007

9. Test on dyno • Experimental conditions: • Engine: 1.9 l, common rail, 8 valves, 85 kW,Euro 4 • Total duration: 130 h • Cycle: Phase 1 - torque @ full/partial load Phase 2 - power @ full/partial load repeated alternatively • regeneration induced after each phase • No oil drain, no top up – samples were taken before • and after each regeneration step Moscow 2007

10. Tests on dyno Engine: 1,9 l Common Rail,8 valves, Euro 4 DPF accelerated cycle - 195 h Moscow 2007

11. Test on roller dyno • Experimental conditions: • Engine: 1.9 l, common rail, 8 valves, 85 kW,Euro 4 • Total duration: 22,000 km • Cycle: NEDC, repeated up to 22,000 km engine stopped every 15 h, cooled down and started again • No oil drain, no top up – samples taken before and after • each regenaration step for analysis Moscow 2007

12. ECE EUDC 4.052 Km 6.955 Km General data Length:11.02 Km Average speed: 33.6 Km/h Time: 20.3 min. Time (s) 195 400 1,180 Test on roller dyno New European Driving Cycle (NEDC) Moscow 2007

13. Field Test A group of Fiat Stilo running with the SAE 5W40, ACEA B3/B4, synthetic oil used in the lab activity was monitored : # 1 – 90,000 km in city driving conditions; # 2 – 99,000 km in combined driving conditions; # 3 – 60,000 km in combined driving conditions. # 4 – 180,000 km in highway driving conditions. Oil drain interval: 30,000 km Moscow 2007

14. Engine 1.9 l Common Rail, 8 Valves, Euro 4 DPF Accelerated test on Dyno - Viscosity behaviour Moscow 2007

15. Engine 1.9 l Common Rail, 8 Valves, Euro 4 DPF Accelerated test on Dyno Bearing at the end of the test Moscow 2007

16. Engine 1.9 l Common Rail, 8 Valves, Euro 4 Roller Dyno test - Viscosity after regeneration Moscow 2007

17. Vehicle: Stilo 1.9 l Common Rail, 8 valves, Euro 4 Roller Dyno Test Bearing at the end of the test Moscow 2007

18. USED OIL ANALISYS (LAB AND FIELD) - VISCOSITY @ 100°C Moscow 2007

19. USED OIL ANALISYS (LAB AND FIELD) - SOOT % Moscow 2007

20. USED OIL ANALISYS (LAB AND FIELD)- TBN DEPLETION Moscow 2007

21. Conclusions – 1 Oil dilution and degradation • dilution due to regeneration and the resulting viscosity decrease are strictly dependent on driving cycle; city conditions are the most severe, not only because of more frequent regeneration steps, but also because of lower evaporation of light fraction of fuel compared to combined and highway conditions, where the oil reaches higher working temperatures; • as a consequence of fuel accumulation, other oil parameters are affected, such as the alkalinity reserve (T.B.N); higher dilution implies more rapid TBN depletion with running hours or kilometers; Moscow 2007

22. Conclusions – 2 Engine protection • under the tested conditions and with the tested oil no relevant wear phenomena occurred; • however engine inspection showed that failure of engine parts such as bearings might be an issue; • therefore, in view of further extended drain interval, oil life monitoring devices, which indicate when oil drain is necessary based on recording and processing engine running conditions, are highly advisable in conjunction with DPF to guarantee engine protection throughout its entire life. Moscow 2007

23. L. Di Stefano, A. Dotta, G. Natoli, G. Pometto, P. Salino M. Fucale, A. Pari Thanks you for your attention! Moscow 2007