Brake dust filter hood with final separator and vortex generator for passive manipulation of the boundary layer
Up to 85% of traffic-induced particulate matter is comprised of dust emerging from brake, tire or road abration. The present brake dust filter hood can help to reduce fine dust emission into the environment. The integrated final separator inside the hood sheds the dust containing boundary layer passively off the disc brake surface and helps with efficient collection of fine dust into the filter media. By additional integration of a vortex generator inside the hood, the boundary layer can be shed off even more effectively.
Recent studies have shown that up to 85% of the traffic-induced particulate matter of PM10 (particulate matter < 10 µm) is composed of tire-, brake- or road-abrasion or by dust being stirred up from road surfaces. The problem of particulate matter thus concerns not only diesel engine vehicles, but also petrol- or electro-powered vehicles. According to studies of the Empa, the Swiss Federal Laboratories for Materials Science and Technology, the fine dust emitted by disc brakes alone, adds up to roughly a fifth of traffic-induced particulate matter in cites. Together with tire abration, a total of over 111.400 tons of dust is stirred up into the air per year in Germany alone. Especially brake dust is particularly dangerous in breathing air, because it is composed to a great extent of particles with a particulate matter of below 0,1 µm (ultrafine fraction of PM2,5 fine dust particles), and can thus penetrate lunge tissue or even enter the blood stream. Additionally, due to brake disc and brake pad compositions, they contain extremely hazardous substances such as nickel, chrome and copper.
To increase the efficiency of a passive filter hood and to present an effective, passive brake dust collector that is even competitive compared to active systems, the present invention proposes a brake dust filter hood with an integrated final separator and optional vortex generator. As presented in Fig. 1, the filter hood follows the brake caliper of a disk brake and partially covers the disc rotor. In contrast to existing filter hoods, the present filter hood not only contains simple filter mats, but is provided with a sophisticated flow control that sufficiently sheds the fine dust-containing boundary layer of the disc surface. For that, first the flow area is decreased by air baffles and then a final separator (6 in Fig. 1B) that is shaped as a blade (7 in Fig. 1B) close to the disc surface, followed by abrupt deflections of the air flow (8 in Fig. 1B), the boundary layer is shed off the disc surface. The blade supports also the sealing of the hood, while the pressure changes inside the hood support the precipitation of the dust particles into the filter mats (9 in Fig. 1B).
An optional vortex generator (B in Fig. 1A and B) can additionally support braking up the boundary layer. The vortex generator can, as a stand alone solution, in addition also be beneficial in simple filter hoods without the final separator. Especially advantages is the embodiment of the filter hood with a pretzel-shaped cross section (Fig. 2B) and a vortex generator in form of an impeller (4 in Fig. 2B). Hereby, a particularly stable vortex can be generated inside the hood, which in addition also supports the air stream inside the internally air cooled brake disc (7 in Fig. 2B), thus reducing thermal stress on the brake.
A first prototype is in development and soon to be tested in the university-belonging wind tunnel.
German patent applications filed
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