Hydrogen Suzuki Evolves

[Hugh Janus]

From the outside, the original prototype hydrogen-powered Burgman scooter is clearly much longer than the standard model. (Suzuki/)

Last October Suzuki unveiled its prototype for a hydrogen-fueled Burgman scooter developed as part of the company’s efforts with the HySE consortium to make hydrogen a viable power source for combustion engine motorcycles and scooters. Now a newly published patent application has revealed a new variation on that design that goes about solving one of the biggest problems with that prototype, namely its size.

The first-gen prototype used just one large hydrogen tank, which severely limited packaging. (Suzuki/)

The original, running prototype for Suzuki’s hydrogen-fueled Burgman ICE scooter—which isn’t to be confused with several generations of hydrogen fuel cell electric scooters that Suzuki has made over the last decade or so—featured an extraordinarily long wheelbase as a result of its fuel system. To fit the large hydrogen cylinder low down in the bike’s chassis ahead of an engine and transmission based on the standard Burgman 400 parts, the first prototype’s wheelbase was extended by a full 8 inches by shifting the whole powertrain and swingarm backward. That’s what this new patent aims to prevent while still retaining the ability to carry a worthwhile amount of fuel.

This illustration shows how Suzuki has positioned the hydrogen tanks (81 and 86) so that the scooter can use a normal Burgman wheelbase and still carry enough fuel to be practical. (Suzuki/)

The solution isn’t a complicated one. Instead of a single, large hydrogen cylinder, the new design features two smaller ones. The first is, like the original prototype, in front of the engine, but to save more space it’s tilted upward at the front to entirely eliminate the wheelbase stretch of last year’s bike. That allows it to fit into a standard, unmodified Burgman 400 chassis, without requiring the engine, transmission, and swingarm to be shifted backward. A second hydrogen cylinder is then fitted in the back, under the rear section of the seat. Seen from the side it’s pitched upward at the same angle as the seat unit but looking down from above it’s skewed to one side, with the front of the cylinder toward the left of the bike, to maximize its size in the available space.

This bird’s-eye view shows how the tanks (81 and 86) are positioned. (Suzuki/)

These fixes illustrate one of the key problems with hydrogen as a fuel. Not only is it much less dense than liquid hydrocarbons like gasoline in terms of volume, so you get less energy in the same amount of space even when the hydrogen is compressed, but the huge pressure it’s stored at means the tanks must have very specific shapes to be able to contain that pressure. While a gasoline tank can be made from lightweight plastic, steel, or aluminum and in whatever shape is required to maximize its volume within the confines of the bike, hydrogen needs to be stored in cylinders capable of withstanding the 10,000 psi of pressure that the gas inside is compressed to.

The new version of the prototype now utilizes the same wheelbase as this standard model. (Courtesy of Suzuki/)

There are other considerations too. The radiator at the front of the bike needs to be isolated from the front hydrogen tank, with a deflector behind it to direct hot air downward rather than letting it elevate the temperature of the hydrogen, for example. And of course the engine is heavily reworked to be able to run on hydrogen, with direct fuel injection to add the hydrogen to the combustion chamber after the inlet valves have closed.

The problem of hydrogen storage remains a sticky one, as illustrated by Kawasaki’s supercharged hydrogen-powered prototype that made its first public demonstration run at Suzuka last month. However, the HySE consortium, which includes all of Japan’s Big Four motorcycle companies as well as Toyota, is working on the problem of fuel systems and refueling, as well as the issue of making viable hydrogen-fueled combustion engines, so improved solutions might yet be found.

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