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The fine dust from car brakes is considered dangerous for the environment and health. Technical There have long been solutions to the problem. But only when Euro 7 comes, these should also be more widespread.
The automotive industry is waiting with some excitement for a trend-setting proposal from Brussels: The EU Commission is expected to present a specific draft for the future in the spring Emission standard Submit Euro 7. The set of rules, which will probably come into force in 2025, is likely to require vehicle manufacturers, among other things, to further reduce fine dust emissions from cars. Despite Euro 6d and a currently rapidly growing number of e-cars, the problem is far from off the table.
The drives are indeed cleaner and thus the fine dust from the combustion tract has decreased, but the abrasion of tires and brakes remains a huge and still unsolved problem. Physicians, scientists, environmental organizations and official institutions repeatedly point out the dangers to the environment and human health from fine and ultrafine particles. Now, as part of the Green Deal, the EU is likely to focus its Euro 7 plans on the issue of increased emissions from automobiles, thereby expanding the fight against particulate matter to include tires and brakes.
Especially for the latter, some solutions have already been developed to the point where they are ready for series production. However, they will only become more widespread when the binding EU regulations actually require their use. The supplier industry senses a correspondingly large business and is already positioning itself to submit suitable solutions to the OEMs. There are several different approaches to counteract brake wear - with advantages and disadvantages and different costs.
Years of trouble
One of the beneficiaries of Euro 7 could be the French company Tallano with its Tamic extraction technology. Company founder Christophe Rocca-Serra came up with the idea for this solution when he was annoyed by dirty rims on his car when visiting customers. From 2012 onwards, he worked with a friend to tackle the dirt problem, and it quickly became clear that the fine dust from the brakes is less of an aesthetic problem and more of a health problem.
The solution to both is active extraction technology that captures the dust in the brakes as soon as it occurs. The brake pads must have a suction duct for this, which is connected to a mini vacuum cleaner via a hose. There is an electrically driven turbine in the engine compartment, which generates the suction pressure during braking in order to direct the fine dust into a filter. Up to 90 percent of the brake dust is supposed to be absorbed by the Tamic principle, which at the same time ensures a significant reduction in the total fine dust emissions.
“In the case of cars, we have measured fine dust emissions from braking that are six times higher than the currently permitted fine dust limit values for the engine,” says Bert Stegkemper, Managing Partner from Germany, who joined Tallano in 2014.
The Tamic system could be integrated into conventional braking systems with manageable effort and could thus make a significant contribution to reducing fine dust emissions in road traffic. There is no significant increase in unsprung masses, the electronics are compact and maintenance is low. “The filter has to be changed every 30.000 kilometers. Thanks to the bayonet lock, it can be unscrewed with a flick of the wrist," says Stegkemper. He puts the additional costs for the car manufacturer at an average of around 150 euros per car.
Although the costs may seem moderate, there is still no brake or car manufacturer that uses the Tamic system. But the increasing pressure to reduce particulate matter with Euro 7 plays Tallano into the cards. In 2021, the somewhat outdated start-up successfully completed another round of financing and, according to Stegkemper, is currently in talks with various players. This also includes railway operators, because the Tamic system can also make railways and metro trains cleaner. Stegkemper even sees great market potential here, because there is growing pressure on municipalities and railway operators to reduce fine traffic congestion in metro stations or train stations. Unlike cars, the Tamic technology could even be retrofitted to existing trains.
Ready for the big career
However, Tallano will not manufacture its cleaning technology for motor vehicle brakes itself. The start-up sees itself as a provider of innovations with a number of patent rights, but not as an implementer. "If a supplier from the automotive industry comes by tomorrow and wants to buy us with the appropriate leverage, then our know-how and some of our employees will be transferred to them. No decisions have been made yet. I think we're still waiting a bit for regulation," says Stegkemper.
The German brake disc manufacturer Buderus Guss also expects that the European Commission's proposal will further narrow the scope for fine dust emissions: "With regard to fine dust emissions, Euro 7 will place demands on the braking system that can only be achieved with additional technical solutions," confirms Olaf Ley, Head of Sales and Application Development at the supplier based in Breidenbach, Hesse.
For years, the brake disc manufacturer has been producing the iDisc as a solution to the problem that is ready for series production. It can already reduce fine dust emissions from car brakes to the Euro 7 level. Unlike the Tallano, which absorbs the fine dust immediately after it forms, the iDisc drastically reduces brake wear and thus the formation of fine dust as it arises. This is made possible by an essentially normal gray cast iron brake disc, to which a hard metal layer and optionally titanium carbide is applied. The resulting surface is very hard and therefore particularly abrasion-resistant. This should result in 80 to 90 percent fewer fine dust emissions, which roughly corresponds to the level of the Tallano solution.
Actually a performance brake
Unlike the solution from France, the iDisc has been on the market for a number of years and is currently available as an option for some Audi and Porsche models. With the Porsche Taycan, it costs an impressive 3.000 euros extra as a "Surface Coated Brake". In any case, this first iDisc generation was not primarily developed as a solution for reducing fine dust, but as a performance brake that is offered as a cheap alternative to the significantly more expensive ceramic brake.
"In addition to advantages in terms of performance, fine dust emissions and corrosion behavior, the iDisc offers a significantly longer service life. It can be designed as a lifetime component and thus makes a contribution to the sustainability and economy of the vehicle over its lifetime,” Olaf Ley praises his brake discs. However, the reduced fine dust emissions have so far hardly been taken into account for marketing purposes for the coated brakes.
costs are reduced
Buderus Guss wants to change that with the iDisc II. This new generation has now left pre-development, and talks are being held with the first customers regarding series development, especially with regard to Euro 7. “We did our homework on the cost side with the iDisc II. The previous generation did not become widespread in the volume segment because a very expensive coating process is used here. We now have an alternative coating process. We also have a gradation, a construction kit. We still offer a performance variant that is close to the first generation in terms of properties.
Then we have an Advanced variant for powerful combustion engines and hybrid vehicles. There is also an e-mobility variant with a single-layer coating for e-vehicles. The focus here is on corrosion protection. Rust is a huge issue in e-cars, since brake discs on the rear axle are rarely used.” At VW, this corrosion problem is currently being avoided by installing drum brakes on the rear axle of e-cars such as the ID.3 and ID.4.
Cost versus Environment
Against the background of the Euro 7 tightening, Buderus Guss is currently holding talks with several car manufacturers. But the iDisc II won't be cheap either, so it probably won't be the optimal solution for every model. "There are different philosophies here, depending on whether the manufacturer is cost-driven or, for example, has a green thumb on the flag." Ley does not name any specific prices, but the elaborately coated disc brakes are said to be two to three times more expensive than conventional cast iron discs .
It remains to be seen whether automobile manufacturers will only use the new brake dust-reducing or avoiding technologies when Euro 7 is mandatory, or whether they, as environmental pioneers, will use them independently of legal requirements. The OEMs have corresponding warehouses for both scenarios. Due to their inherent braking behavior, electric cars will probably not need clean brakes, but they will need a rust-inhibiting coating on the friction surfaces that are subject to little stress.
Special coating
Tallano and Buderus Guss are not the only ones working on solutions to reduce fine dust from brakes. Among other things, the filter specialist Mann+Hummel has developed a passive filter system in which the fine dust collects in a housing on the top of the disc brake. Similar to Buderus Guss, the company C4 Laser Technology, based in Freital, Saxony, uses a coating process for brake discs that is intended to reduce the formation of fine dust from brake abrasion.
Finally, the German Aerospace Center (DLR) is developing a mechanical disc brake with oil bath bearings as part of the Zedu-1 project. The closed system should even filter out 100 percent of the abrasion. It will be exciting to see which manufacturers will choose which solutions for which models in order to be able to clear the Euro 7 hurdle in a few years.