Kawasaki Ramps Up Hybrid Development

[Hugh Janus]

Kawasaki’s latest patent application shows a complete rethinking of motorcycle engine basics. (Japanese Patent Office/)

Despite revealing its decade-long electric bike development project a year ago, Kawasaki has since emphasized that it had no production plans for a purely electric-powered motorcycle. Now the company’s R&D appears to be increasingly focused on hybrids that combine conventional gas engines with electric motors to improve performance, economy, and emissions without the need to lug big, heavy batteries around.

Kawasaki’s patents show a traditional manual transmission with clutches to connect the combustion engine, the electric motor, or both. (Japanese Patent Office/)

Over the years Kawasaki has worked on several hybrid projects, ranging from economical single-cylinder machines to superbikes that could benefit from an electric boost. None have even reached the show stands, let alone production, but recently the firm’s research activity on the subject has accelerated. The latest set of patents show an array of new developments including increased concentration on controlling a bike with not just one but two power units on board.

Related: Where Are The Hybrid Motorcycles?

As with many hybrid cars, the idea is to make a machine that can run on its combustion engine alone, on purely electric power, or with both systems working together for maximum performance. Relatively small batteries can be charged via regenerative braking or by using the internal combustion engine to ensure there’s always electricity on tap when needed. However, while cars such as Toyota’s Prius often combine their power units using an automatic gearbox or continuously variable transmission, Kawasaki is keen to keep the rider involved on any hybrid bike it develops. Hence the normal, manual transmission is retained, with clutches to connect the combustion engine, the electric motor, or both to its input shaft.

The electric motor’s batteries can be charged via regenerative braking, so there’s always electricity (and torque) on tap if needed. (Japanese Patent Office/)

That decision aligns with the all-electric prototype Kawasaki showed last year.  Unusually, it combined an electric motor with a conventional foot-shifted transmission and hand-operated clutch, with the intention of creating a familiar riding experience. However, the prototype’s electric motor was relatively small, lacking performance compared to current state-of-the-art electric bikes from firms like Zero. If that electric prototype is only half of the equation, and Kawasaki intends to combine that low-powered motor with an internal combustion engine, it makes a lot more sense.

Another patent detail reveals plans for a performance-enhancing boost button near the throttle grip. (Japanese Patent Office/)

One of Kawasaki’s latest patents focuses on the controls for a future hybrid bike, revealing a four-way rocker switch for riding modes attached to the throttle twist grip, allowing a rider’s thumb to remain on it at all times. Even more intriguing is a separate “boost” button fitted below the mode switch. The patent explains that hitting that “boost” will allow several seconds of additional performance from the electric motor. Various safety nets would stop the boost when it’s not needed, such as when the rider rolls off the throttle or hits the brakes.

An electric motor’s max torque at zero revs, combined with a gas engine’s different torque curve, can yield the best of both worlds. (Japanese Patent Office/)

Another of the company’s new patents shows how the electric motor uses its main performance benefit of maximum torque at zero revs. It combines with the gas engine’s torque curve, which rises with rpm, to give the best of both worlds, as electric torque drops off rapidly at higher speeds.

How Kawasaki envisions the hybrid’s different motor and system scenarios in operation. (Japanese Patent Office/)

Kawasaki started developing its electric bike around 10 years before showing a prototype in public. Patents for the firm’s supercharged H2 started to emerge a full five years prior to its launch. So the recent rush of hybrid patents doesn’t mean we’ll see the fruits of Kawasaki’s labors right away. In five years or so, though, they could be a reality.

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[Tym]

Hub motors, central power unit, no driveline, vroom.... 

[XTreme]

I wouldn't raise your hopes......30 years and they still can't sort out a doohickey!