Contribution of Open Crankcase on the Emissions of a Euro VIE Truck

Some European Heavy Duty (HD) vehicle manufacturers have adopted Open Crankcase Ventilation (OCV) systems to improve reliability and performance. The emission compliance of HD vehicles both during certification and In-Service Conformity (ISC) testing need to also account for the crankcase ventilation. Despite that, the contribution of crankcase emissions to the overall emissions profile of modern trucks remains underexplored. This study experimentally characterizes the crankcase emissions of a Euro VI Step E HD truck equipped with an OCV system under controlled conditions on a chassis dynamometer. Emissions were measured over the World Harmonized Vehicle Cycle (WHVC) and an ISC-compliant driving cycle at two test cell temperatures. The results indicate that crankcase emissions account for up to 4% and 8% of the current regulatory limits for nitrogen oxides (NO_x) and 23 nm solid particle number (SPN₂₃), respectively. The tightening of NO_x limits under Euro 7 regulations would increase these contributions to approximately 11%. SPN₁₀ crankcase emissions were found to be on the order of 10¹¹ (11% of the Euro 7 limit). Real-time SPN₁₀ and SPN₂₃ measurements revealed that the fraction of nanosized particles increases significantly during cold start, suggesting increased oil combustion within the cylinder. These findings highlight the need to refine crankcase emissions measurement procedures within regulatory frameworks. A systematic investigation of measurement setups and ageing effects, taking into account variations in OCV system designs and piston ring wear, is essential to determine whether characterization during certification is sufficient or if ISC testing throughout the vehicle’s useful life will be required.