The patents were discovered on the US Patent and Trademark Office's website and published by Autoblog.
The first patent was filed on September 11, 2015, and is for an electric drivetrain with a rotary engine acting as a generator to recharge the car's battery.
In the accompanying patent diagram, we can see that the car's electric motor is mounted up front, while the rotary engine, fuel tank, and inverter are laid out across the rear axle.
This setup is nearly identical to the one used in the 2013 Mazda 2 RE Range Extender prototype.
The second Mazda patent, filed on September 7, 2016, is for an automatic stop/start system for rotary engines. As rotary engines don't have valves like petrol and diesel engines, they rely on the spin of the rotor itself to open or close off the intake and outlet tracts.
Mazda's patented stop/start system ensures that the rotary engine's rotor stops in such a way that the inlet line is closed off. The system could also include a spark plug to burn off any left over fuel inside the combustion chamber.
While these patents may hint at what some of what Mazda's research and development team is currently busy with, these drivetrains may never reach production even if they are technically feasible.
In November 2016, Kiyoshi Fujiwara, Mazda's head of research and development, told CarAdvice that the Hiroshima-based car company will introduce its first EV model in 2019, although this model may be co-developed with Toyota due to projected low volumes.