Balancing of Engine Oil Components in a DI Diesel Engine with Exhaust Gas Aftertreatment 2007-01-1923

The influence of oil related emissions became more important in the past due to reduced engine-out emissions of combustion engines. Additionally the efficiency of exhaust gas after treatment components is influenced by oil derived components. A balancing of relevant engine oil components (Ca, Mg, Zn, P, S, Mo, B, Fe, Al, Cu) is presented in this paper. The oil components deposited in the combustion chamber, in the exhaust system as well as in the aftertreatment devices were determined and quantified. Therefore a completely cleaned DI Diesel engine with oxidation catalyst, Diesel particulate filter (DPF) and NO_x adsorber catalyst (LNT) was operated in different operating conditions for 500 h in a development test cell. The operation included lean/rich cycling for NO_x trap regeneration. After finishing the 500 h test procedure the engine was completely disassembled and all deposits were analyzed.

During the investigations about 87 % of the emissions source oil can be assigned to the individual deposit places drained oil, combustion chamber, tail pipes, turbocharger, EGR system, oil filter, DOC, LNT and DPF. The main part of the deposits are found in the discharged oil. Up to 18% are assigned to the DPF (67% of the exhaust emissions). These elements also gave a good correlation compared to the total weight difference of the DPF. However the elements Mo and P accumulated also in the DOC and LNT, which leads to catalyst poisoning. The LNT adsorbed 93% of the emitted S whereof 67% are derived from the engine oil. Deposits in the combustion chamber, the exhaust pipes, the EGR-system, the turbo charger, and the oil filter are of lower importance with a maximum fraction of lower 4%.