**5. Conclusions**

The creation of a blowby simulation model based on a TGDI engine made it possible to characterise the quantity of oil swept by these gases. This was performed at different engine operating points and as a function of the endgap position of both the compression and the sealing rings. Under full load at 2000 rpm, the quantity of oil swept can be as high as 20 μg. cycle−1. At idle speed, the sweeping intensity is close to zero and there is a phenomenon of oil storage on the piston crown. The experimental results confirmed this observation and showed that the quantity of oil stored on the piston crown depended on the idling time. For example, the evolution of the idling time from 7 s to 22 s between two strictly identical accelerations generated three times more particles. The new Euro 7 standard should limit particulate emissions to 3 mg.km−<sup>1</sup> and 6 × <sup>10</sup><sup>11</sup> particles.km−<sup>1</sup> on a WLTP cycle for particles >10 nm, instead of 23 nm previously. As there are eight idling stages with a total duration of approximately 224 s in a WLTP cycle, this phenomenon must be taken into account. At present, it is not possible to differentiate the oil pumping mechanism by the piston rings from the oil sweeping mechanism by the blowby gases at idle. A future study on a single-cylinder spark ignition engine will characterise the impact of each mechanism.

**Author Contributions:** Conceptualization, V.B. and D.C.; formal analysis, V.B.; investigation, V.B.; methodology, V.B.; project administration, V.B., D.C. and J.-F.H.; resources, D.C. and J.-F.H.; software, V.B.; supervision, V.B., D.C. and J.-F.H.; validation, V.B., D.C. and J.-F.H.; visualization, V.B., D.C. and J.-F.H.; writing—original draft, V.B.; writing—review and editing, V.B., D.C. and J.-F.H. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
