Influence of the Run-in Methodology on the Particle Number Emission of Brakes

Abstract

The share of exhaust particles of particulate pollution caused by traffic is declining due to electrification and improved exhaust after treatment. Sources like tire, road and the brake are moving into the socio-political focus. For this reason, the UNECE mandated the Particle Measurement Program (PMP) to investigate brake particle emissions. Their task is to develop a methodology, including a cycle, to measure particulate emissions from vehicle brakes. In addition to the emission measurement cycle, a run-in procedure for the brake is also necessary to ensure a stable friction and emission behavior. The PMP proposes to repeat the WLTP-Brake cycle five times, which is time consuming and has not yet been sufficiently evaluated for its suitability as a run-in procedure. Therefore, the aim of this study is to investigate the influence of different run-in procedures on particle emission. This is done by measuring the particle number concentration of new brakes after different run-in procedures at a test stand with an enclosed constant volume sampling system. The results show that the run-in methodology strongly influences the emission behavior in terms of the stability of the following measurements and the reproducibility.