Mazda says the future of its hallowed rotary engine depends on a portable electricity generator powered by a scaled-down Wankel engine. The same downsized single-rotor engine that serves as a range extender in the Mazda2 EV concept has been applied to a compact electricity generator that could be used to power homes, camp sites or emergency shelters. Although it’s just a concept, Mazda says its first portable generator is highly competitive and central to the business case for producing its first range-extender EV, which could be based on next year’s all-new Mazda2.
“We cannot do one without the other,” said Takashi Suzuki, the program manager of Mazda’s Powertrain Development Division.
Mazda continues to develop a full-size twin-rotor Wankel engine to power a belated replacement to the RX-7 and its last rotary sports car, the RX-8, which was discontinued last year. However, it refuses to say how many engineers are currently allocated to that project, and any new-generation rotary-powered Mazda sports car would not appear before 2017 – the rotary engine’s 50th anniversary year and the year before the RX-7’s 40th birthday in 2018.
For now, Mazda’s only publicly revealed rotary engine powers both the concept generator and a single prototype version of the Mazda2 EV, in which it doubles the driving range to 400km. Relatively lightweight at around 100kg, the 330cc single-rotor engine is mounted on its side under the rear of the Mazda2 EV, via three mounting points, eliminating vertical vibration. In its portable generator application, it measures just 700mm tall, 300mm wide and 400mm deep, and is fitted with a belt drive system to rotate the generator at double speed.
It is equipped with a nine-litre fuel tank that can feed the downsized rotary engine (which is about a quarter of the capacity of the 13B rotary that powered the RX-8 and the lease-only hydrogen-powered Premacy plug-in hybrid) a range of fuels including petrol, butane or propane. Apart from its compact size, light weight and ability to run on multiple fuel types, Mazda cites noise as a major advantage, following testing that shows it’s at least 5dBa quieter at the same revs than an equivalent petrol or diesel piston engine.
More importantly, with an output of 22kW at a constant 4500rpm and peak power of 28kW at 6000rpm, Mazda says it is as powerful as fixed diesel generators that cost more than $10,000, weigh up to 580kg and require a trailer to transport, as well as being far more powerful than conventional petrol generators around the same weight and – potentially – price.
“This is a further concept of the rotary engine electric generator,” said Suzuki-san. “We are considering this system could also be used as a portable electric generator.
“We think there is a market for a rotary engine electric generator. A lot of electric generators are sold in the marketplace. There is no mobile electric generator that can produce 15-20kW-plus (of) electric power.”
Mazda’s application of a rotary engine as an EV range extender is not a new concept. Audi did the same with its first-generation A1-etron concept, but has now abandoned the idea in favour of a conventional small petrol engine.
The Japanese brand says it remains committed to the rotary engine and, as the producer of more rotary-powered models than any other car-maker, has a duty to continue its custodianship. The first rotary engine was patented in 1929 by German engineer Felix Wankel, who licensed to the technology to Mazda and German car-maker NSU, which evolved into the Audi brand after it produced the rotary-powered Ro80 in 1977. Mazda built almost 812,000 two-seat RX-7 coupes between 1978 and 2002, and more than 192,000 four-seat RX-8s between 2003 and 2012, notching up more than a million rotary car sales since the Cosmo Sport rotary in 1967.
