Mazda has announced that its rotary engine technology – last featured on the RX-8 sports car – is to make a return as a range extender for a soon-to-be launched electric vehicle (EV).
The company plans to enter the EV market in 2020 with two new cars: one powered solely by battery and the other pairing an electric powertrain with a rotary engine that will be used to recharge the battery when necessary to increase the vehicle’s driving range.
Although precise technical details have not yet been revealed, the engine is expected to be a variant of the Wankel rotary engine, a design in which the four strokes of an Otto cycle piston engine occur in the space between a three-sided symmetric rotor and the inside of a housing.
The key attraction of an engine based on this design is its high power to weight ratio – a characteristic that made it popular with designers of some of the first fighter aircraft – but its wider uptake has been hampered by maintenance issues and concerns over fuel and oil consumption.
Mazda claims that the relatively light weight and small size of a rotary engine make it ideal for a so-called shared packaging layout. It added that the engine will be able to run on liquefied petroleum gas and provide a source of electricity in emergencies.
The firm is one of a handful of car-makers to seriously develop rotary engine technology. It launched its first rotary powered vehicle – the Cosmo 110S – back in 1967, and used the technology in the RX-8 sports car until it was discontinued in 2012.
Other companies to experiment with the technology in recent years include Audi, which showcased a rotary engine range-extender on its A1 E-Tron concept car back in 2010; and Lichfield-based Advanced Innovative Engineering which, as reported by The Engineer, recently carried out the first ever demonstration of a rotary engine on a British-built car.
The latest announcement is part of Mazda’s so-called “Sustainable Zoom-Zoom 2030” project, an effort to ensure that 95 per cent of the vehicles it produces by 2030 will feature some form of electrification alongside internal combustion engines. Full electric vehicles will account for the remaining 5 per cent.
Will the new rotary engine be able to run on hydrogen?
Wankel Rotaries are really adept at using many different fuel sources and have run on Hydrogen before: https://en.wikipedia.org/wiki/Mazda_RX-8_Hydrogen_RE
So it’s definitely a possibility if it came down to it. Though this is just a part-time engine anyway, only for going long distances when you get low on charge.
I should point out that the rotary piston engine used in early fighters was quite different to the Wankel engine. The early rotary engine had radially arranged cylinders which rotated while the crankshaft remained stationary. The propeller was attached to the cylinders. This type of engine was obsolete by the end of the first world war.
many thanks to CD for this information. As a child, I recall pictures and diagrams of these engine types on early aircraft, but must confess that I never really understood how they worked. I must confess also that when told as a child that railway steam engines had a piston, I believed for some time that this was contained within the large boiler diameter (not at the side front!)
Wankel engines are well known for their high emissions. Unfortunately, this extremely short article says nothing about its emission levels and how would Mazda solve that problem. It has been claimed that high emissions was the reason for stopping the production of those engines.
They’ve had these engines in R&D for years and claimed recently that they’ve worked out the three big issues with rotaries with their plan for re-releasing them. Reliability, Fuel Economy and Emissions have apparently been fixed, but they’re kinda short on money and are banking on the success of Skyactiv-X and this new EV vehicle they’re building with Toyota to bankroll their passion in Rotary engines.
The big difference is that Wankel engines are poor economically when used at constantly varying RPMs, while an engine used for charging batteries wouldn’t have that issue.
As posted above: no mention of emissions. Neither is there any mention of the other bane of Wankels in the form of relatively short lived for the tip seals (and presumably all other rotor seals).