It goes without saying that in the motorcycle world, BMW has become synonymous with the boxer engine. No other manufacturer currently in production makes use of a flat-twin boxer engine similar to what BMW uses in a variety of its models. That being said, given the dawn of electrification, BMW doesn’t seem ready to give up on the boxer engne just yet. That’s right, recent patent filings suggest that the German manufacturer is developing an all-electric boxer engine, and it’s pretty exciting.
In theory, a BMW boxer electric motor is certainly really cool. From a branding perspective, it’ll allow BMW to retain its timeless look, as the design of the electric motor will stick out on either side of the bike. However, more importantly, in terms of cooling, it is quite practical. Electric motors have very significant cooling challenges, and even the most cutting-edge and high-tech battery packs can and do become quite hot when in use and charging. They tend to become even hotter if you use fast chargers. As a result, proper heat control is a critical component of EV design.
In order to achieve optimal cooling in its electric motorbike applications, BMW's patent proposal recommends numerous alternative configurations. All rely on exterior cooling fins, which exploit the circulation of air over the motorcycle while it's in motion, in order to further provide cooling to whatever is housed underneath. In this case, it could be the main electric motor, a battery pack, the bike's ECU, or even extra liquid cooling. Consider it a backup cooling system in the latter situation.
Alternatively, BMW proposes that certain portions of the electric powertrain be placed in the boxer section, benefiting from mechanical cooling provided by the lightweight and compact casing, while other components could utilize a separate liquid-cooling system entirely. By mixing both methods of cooling into an electric motorbike design, it may theoretically reduce weight, concentrate mass, and have the most effective cooling possible to improve a future electric motorcycle drivetrain.