The finalists: Start-Stop Operation in Fuel Cell Vehicles

Laureates: Jörg Schütz, Hans-Frieder Walz

 

When it comes to efficiency, no other vehicle drive concept can compete with the fuel cell engine. That’s why many Daimler teams are working flat out to take this technology to the series-production stage (see report on page 54). However, as development engineer Jörg Schütz (left in picture) and his research colleague Hans-Frieder Walz rightly observe, “No technology is so good that it can’t be enhanced.” It was this thought that inspired their “Start-Stop Operation in Fuel Cell Vehicles” project – an undertaking that propelled them into the finals of the Daimler Research Award. Their achievement is to have tweaked this innovative drive system so that it operates in a manner that not only reduces the consumption of energy – in this case, hydrogen – by up to 11 percent but also, as a welcome side benefit, enables the system to operate more quietly.

Now, the Mercedes-Benz F-Cell is already a pretty quiet customer by nature. Indeed, the noises emanating from the vehicle could hardly sound less like an internal-combustion engine. Anyone who has ever ridden in a fuel cell car knows exactly what Schütz means when he says: “You start picking up on noises that you’ve never heard before, because they are usually drowned out by a conventional engine.” One of these sounds is produced by the compressor, which forces air into the fuel cell engine to feed the process of “cold” combustion. During the periods when the vehicle only requires a small amount of electric power – because it is in stop-and-go traffic and running purely on battery power, say, or coasting downhill – the fuel cell engine can be switched off, along with the compressor, just like in a conventionally powered or hybrid car fitted with a start-stop function. This not only saves energy in the case of the fuel cell but also means that the compressor can take a break, with the result that the component’s audible hissing is interrupted.