The rotary engine has already been confirmed to make a comeback as a range extender for the Mazda MX-30. Made famous by cars like the Mazda RX-7 and RX-8, the rotary engine was revolutionary, but it also presented a host of challenges, mostly in terms of fuel economy and environmental performance. Keen to make the rotary engine relevant to this day, Mazda has done a few weird tricks to make it fit for today’s strict environmental regulations.
CarBuzz was able to uncover patent filings for the upcoming range extender version of the MX-30, which not only showcases the engine’s role in the subcompact electric SUV but also how Mazda managed to improve the engine’s environmental performance by adopting its own unique take on a technology we now take for granted–variable valve timing (VVT).
VVT has never been implemented in a rotary engine until Mazda showed up with this patent for the MX-30, which showcases that the lightweight and compact single-rotor engine will feature a dual-intake port arrangement. The rotor tip passes the primary port first before the secondary port deeper into its rotation. The purpose of the secondary port is to prolong the intake stroke, thus allowing more air into the combustion chamber during high-power situations.The secondary port, however, interferes with efficiency in low-power situations, which is why Mazda developed a throttle valve that closes the secondary port if it isn’t needed.
What’s even more interesting is Mazda even went through the pain of adding an electric motor that assists the rotary engine, and it’s driven by a high-voltage traction battery through its own inverter. The electric motor’s purpose is to apply either positive or negative torque to the rotor’s output shaft. This has the effect of varying the speed at which the rotor spins to optimize the intake charge entry into the combustion chamber.
If this all sounds familiar to you, that’s because Mazda just implemented variable valve timing into the rotary engine for the first time. The technology’s goal is to vary the intake stroke of the rotor, thus making this engine efficient in a wide variety of power demands.
A possible con of this implementation though is that the sudden changes in the speed at which the rotor spins can lead to oscillations in the engine. But then, the rotary engine doesn’t drive the wheels, so it’s most likely that drivers won’t feel the engine’s oscillations altogether.
Mazda’s implementation of the rotary engine is similar to Nissan’s e-Power technology that’s found in the Kicks. What’s different is that Mazda’s solution is very weird, and we love them for that.