Mazda MX-30 R-EV: the return of the rotary

Mazda, the latest manufacturer to develop the Wankel engine, is reintroducing it as a range extender for the MX-30 R-EV plug-in hybrid.

By Yves Maroselli

The R-EV version of the Mazda MX-30 has a reduced-capacity battery, the autonomy of which can be extended via a generator driven by a rotary engine.
© Mazda

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LMazda engineers have never stopped believing in this. After deciding to see their expensive rotary piston engine disappear with the RX-8 coupe in 2011, they finally found an opportunity to modernize it in the form of extended range for the MX-30 R-EV. . This engine concept developed by the German Felix Wankel had its heyday in the 1960s – NSU (RO80), Mazda (Cosmo then RX) and even Citroën models with the GS Birotor – but has since been gradually abandoned. high oil consumption leading to high pollutant emissions, but also lower thermodynamic efficiency than a conventional reciprocating engine.

Compact and light engine

The two points that the Japanese engine manufacturers have announced are significant improvements, thanks to the wider gaskets that ensure better sealing of the combustion chamber on the one hand, and the adoption of direct injection on the other hand, the specific consumption (in terms of produced kWh) has been reduced by 25% compared to the RX-8 unit. ! The traditional qualities of a rotary engine are highly desirable for a range extender that starts up infrequently: no vibration, compactness, and lightness. Thus, Mazda reckons that the single rotor of the MX-30 R-EV unit is 830 cm.3 Developing a maximum power of 74 hp (55 kW) at 4,700 rpm and weighing only 71 kg, it is 18% more compact than the equivalent 3-cylinder engine. Ironically, this motor can be installed under the front hood of the car and in the same housing as the 170 hp electric motor (25 more than the MX-30 BEV), it cannot drive the latter mechanically and therefore cannot drive the wheels as above . latest Honda hybrid systems. It’s up to Mazda to preserve the feel of the electric traction chain. As a result, the rotary engine is content to turn the generator and act as a simple generator.

85 km electric range

Compared to the 100% electric version of the MX-30, the lithium-ion battery has reduced its capacity from 35.5 to 17.8 kWh to make room for the 50 liter tank that powers the rotary engine. That’s why Mazda presents the MX-30 R-EV as a rechargeable hybrid with a 100% electric range of 85 km and a range of over 600 km. Official CO emissions2 According to the WLTP cycle, it is 21 g/km. These figures imply fairly high consumption of the rotary engine when the battery is discharged (about 9 l/100 km, due to the low efficiency of the rotary engine and its electric drive), but again this is a relatively rare use case. , this happens only when the autonomy allowed by the battery capacity is exceeded. Depending on the situation, it is enough to find a service station or an electrical outlet. Charging can be done in 2 hours 45 hours at 7.4 kW single-phase alternating current, 1 hour 45 hours at three-phase 11 kW or half an hour at 36 kW direct current. Finally, a socket in the trunk can be used to supply electrical consumers up to 1.5 kW (V2L function for the truck). The MX-30 e-Skyactiv R-EV (that’s its full name) should go on sale in mid-2023 at a price starting from 38,250 euros, like the BEV version, but, unlike the latter, without the right to the smallest bonuses.

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