Abstract
In this study, different disc brakes and friction materials are evaluated with respect to particle emission output and characteristic features are derived. The measurements take place on an inertia dynamometer using a constant volume sampling system. Brake wear particle emission factors of different disc concepts in different sizes are determined and compared, using a grey cast iron disc, a tungsten carbide-coated disc and a carbon ceramic disc. The brakes were tested over a section (trip #10) novel test cycle developed from the database of the worldwide harmonized Light-Duty vehicles Test Procedure (WLTP). First, brake emission factors were determined along the bedding process using a series of trip-10 tests. The tests were performed starting from unconditioned pads, to characterize the evolution of emissions until their stabilization. In addition to number- and mass-related emission factors (PM2.5–PM10), the particle size distribution was determined. Another focus was the evaluation of temperature ranges and the associated challenges in the use of temperature readings in a potential regulation of brake wear particle emissions. The results illustrate the challenges associated with establishing a universal bedding procedure and using disc temperature measurements for the control of a representative braking procedure. Using tungsten carbide coated discs and carbon ceramic discs, emission reduction potentials of up to 70% (PM10) could be demonstrated along the WLTP brake cycle. The reduction potential is primarily the result of the high wear resistance of the disc, but is additionally influenced by the pad composition and the temperature in the friction contact area.
Highlights
Introduction iationsAirborne particulate matter has long been associated with negative environmental and health impacts [1]
The drop in the emission factors observed for the disc brake can be explained by two reasons
The bedding process can be assigned a high significance with regard to the particle emission behaviour
Summary
Introduction iationsAirborne particulate matter has long been associated with negative environmental and health impacts [1]. Road traffic and transport are one of the main sources of airborne particulate matter in urban areas [2,3]. Different studies show that other vehiclerelated sources of particulate matter are a significantly higher contributor to traffic-related emissions. These include particulate brake wear [5]. Since most of the emitted particles belong to the size classes of particulate matter (≤10 μm) and differ significantly in their physico-chemical properties from automotive exhaust emissions, this source is of particular relevance to human health and is the focus of scientific studies [6,7,8,9,10,11]
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