In urban areas, the impact of on-road vehicles on particulate matter is well acknowledged. Particulates originating from vehicles come not only from the engine exhaust emissions, but also from wear processes in brakes and between tires and road surface. In the EU, these non-exhaust vehicle emissions equal approximately 50 % of the exhaust emissions of PM10 (particles with aerodynamic diameters smaller than 10 μm).

To reduce the air pollution, tail pipe emissions are today regulated. Detailed test protocols for engine exhaust verification and certification, using different driving cycles, are available. However, there are no formal test protocols for particulate emissions from disc brakes.

Here a test cycle for disc brakes is proposed considering a typical European car usage. It consists of nine different braking blocks, starting from a burning-in and involving town, country road, highway and hill descend conditions.

To evaluate the test cycle, a front brake assembly was set-up in a shaft-type inertia dynamometer. Particle emissions were continuously registered using a particle counter, which can measure particulate matter from ultrafine to coarse size

The conclusion is that the proposed test cycle can be used to evaluate particulate emissions from disc brakes, and the next step towards a test protocol should be to improve the measurements using a clean environment around the brake assembly and isokinetic sampling.

Mattia Alemani, Guido Perricone, Aessandro Ciotti - Brembo S.p.A Ulf Olofsson, Anders Söderberg, Jens Wahlström - Department of Machine Design, KTH Royal Institute of Technology