European legislation imposes increasingly strict limits regarding the emission of damaging gases by vehicles. Accordingly, the automotive industry performs considerably research into green technology. They do this together with universities and research centres such as Flanders Make. VCST (Volvo Cars Sint-Truiden) is a global designer and manufacturer of motors, drives and technology components. They work closely together with Flanders Make on technologies for noise reduction in gearboxes.
Cars are today more comfortable, quieter and safer than 10 years ago. Initially, this also made them heavier, which in turn increased their fuel consumption. Today, we’ve reached a turning point. There is general consensus that green cars are the future. Electric and hybrid cars emit less or even zero CO2 and therefore reduce our dependence on fossil fuels.
“There are two conditions that must be met to enable the widespread market introduction of electric drives”, says Dirk Torfs, CEO of Flanders Make. “On the one hand, the cost of the battery must decrease significantly and, on the other hand, this battery must also have a longer autonomy so that the fear of an empty battery is eliminated. We perform comprehensive research into these issues. Hydrogen fuel cells may be the next step. Still, we’re not quite there yet. It will take some time before this technology will be sufficiently mature and financially feasible. Meanwhile, it’s up to public authorities to stimulate such new technologies, for instance by allowing current electric cars to use bus lanes.”
A major additional benefit of electric and hybrid cars is that they are quiet. However, this benefit also entails a potential problem for the safety of other road users and the driver’s comfort.
We’ve become so used to the sound of cars that – leaving aside extremely noisy vehicles – we’ve almost stopped registering it. And yet, we do listen to cars when cycling or walking on public roads. The engine noise helps us to estimate how far an approaching vehicle is still removed from us or to notice a vehicle approaching from behind. A study of the American National Highway Traffic Safety Administration showed that accidents with pedestrians and electric cars might increase by 37% compared to accidents with pedestrians and cars with a conventional combustion engine. In the run-up to a fully electric vehicle fleet, the urban infrastructure and traffic policy will have to be adapted.
Another problem is the noise within the vehicle. Electric cars do not make noise but also cars with a conventional (or hybrid) combustion engine have become much quieter. As a result, other driving noises become more prominent and are often considered a nuisance. Flanders Make works together with KULeuven on a lightweight metamaterial that reduces noise and vibrations. It works as a sound-insulating headset: it eliminates the vibration noise by producing a substitute sound. Tests have shown that this metamaterial isolates equally efficiently as traditional isolation but at only half the weight. This is another way to reduce fuel consumption.
Gears are another source of noise, with the gear wheels as the main noise source. In the final phase of the gear wheel production process, the gear flank is subjected to a specific treatment. This decisive step has a direct impact on the quality of the gear wheels and the noise that they produce. The concept is comparable to asphalt. This used to have a uniform hard structure. Currently, low-noise asphalt is rather porous. Structure plays an important part in noise reduction efforts.
To be able to warrant the high finishing quality of the grinding process of the gear flank, VCST develops together with Flanders Make a permanent quality assurance method. This allows to inspect individual pieces swiftly and easily and thus avoids the need to reject the whole batch. This saves time and money. (If you want to know more about condition monitoring, you can read the whole story here.)
Do you want to know more about the vision of Dirk Torfs, CEO of Flanders Make, on the car of the future? Discover it in Insights.
Dirk Torfs - CEO