Mazda patents triple-rotor hybrid powertrain

Fresh patent filings from Mazda suggest the carmaker still has ambitions to offer a rotary-powered, rear-wheel-drive coupe.

The patent drawings, uncovered by Japanese blog Hatena, show a rear-driven coupe using a three-rotor engine mated to a hybrid system, in what could turn out to be the long-rumoured RX-9.

Mazda has only ever offered a production triple-rotor once before – an optional 20B engine available in the Japanese-market Eunos JC Cosmo, built between 1990 and 1996. The more common 12A and 13B engines offered in the RX-7 and RX-8 were twin-rotors.

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1990 Eunos Cosmo – Japan-only luxo coupe features the largest road-going rotory: a 20B triple.

In November, Mazda joined Toyota, Subaru, Kawasaki, and Yamaha in pledging to keep the internal-combustion engine alive by committing to the development of hydrogen fuel.

Unlike hydrogen fuel-cell vehicles, which convert the fuel to power electric motors, the Japanese manufacturers have been pursuing the development of hydrogen as a direct replacement for petrol and diesel. As hydrogen combusts with virtually no emissions, it would allow the rotary to be compliant with strict Euro 7 emissions laws, expected to come into force in 2025.

In July 2021, Japanese publication Best Car reported Mazda was working on a hydrogen-powered rotary engine – a concept the carmaker first began exploring back in 1991.

Mazda produced a limited run of RX-8 sports cars powered by hydrogen in 2008, as well as building a Premacy people mover with a hydrogen rotary engine with hybrid assistance.

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The latest patents from Mazda showing a hybrid three-rotor powertrain powering the rear wheels.

While patent filings are no confirmation these things will be made, in August, Hatena Blog revealed more patent sketches from Mazda showing a coupe with a strong resemblance to the RX-Vision concept shown in 2015.

The company has also trademarked a symbol in recent months which combine a rotor with an ‘E’ for electric, while another logo has similarities to the Spirit R – special variants of the RX-7 and RX-8.

Rumours of a new rotary-powered RX model have been circulating for years, but despite the many patents and trademarks, Mazda has yet to confirm whether such a model will be produced in the future.