Mazda’s breakthrough in 2019: a diesel engine that runs on gasoline

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Mazda says it will bring new engine technology to market in 2019 that uses diesel-like compression ignition technology – high compression ratios, rather than a spark plug – but with gasoline as the fuel. The engine could improve fuel economy by 20 to 30 percent, Mazda estimates.

Mazda sees the homogeneous charge compression ignition (HCCI) motor as a bridge to a more complete electric future in 10, 25 or more years. The little Mazda has apparently mastered a technology that a dozen major automakers have tried, but haven’t been able to implement yet. Part of Mazda’s magic is keeping a spark plug in each cylinder to ignite fuel when the engine is cold. Mazda will call the SkyActiv-X technology and its long-term plan “Sustainable Zoom-Zoom 2030”.

Electrification imperative. The combustion engine comes first.

“We believe it is imperative and fundamental for us to pursue the ideal internal combustion engine,” Mazda R&D director Kiyoshi Fujiwara said at a press conference on Tuesday. “Electrification is necessary, but the internal combustion engine must come first.”

Sales of electric vehicles worldwide are on the rise, reaching 1 million in 2015 and 2 million in 2016. But that’s not much when more than 85 million combustion engine cars – gasoline, diesel, hybrids – have were sold worldwide last year. Hence Mazda’s desire to bring out a technology applicable to the majority of vehicles.

Spark ignition vs HCCI engine (source: Mazda)

How HCCI works

In a spark ignition system that burns gasoline, the piston compresses the air in the cylinder to about one tenth of its original volume, a fuel injector sprays in a mist of gasoline, the spark plug puts out the fuel-air mixture fires and the piston is driven downward, producing power. Decades of R&D have gone into achieving a more even and even air mixture, determining the best time(s) to inject fuel, how to disperse the fuel, and how to design the piston and cylinder head to maximize fuel consumption for greater efficiency. But other returns on economy and horsepower are getting harder and harder to come by.

Diesel’s higher compression ratio, up to around 20:1, allows more of the energy stored in the fuel to be utilized. High compression temperatures ignite the fuel. But diesel technology suffers from higher emissions of nitrogen oxide or soot particles. Most automakers clean emissions by adding a small dose of urea or diesel exhaust fluid (DEF) as exhaust gases pass through the tailpipe.

Mazda’s homogeneous charge compression-ignition engine ignites gasoline by compression, just like diesel. Unlike diesel engines, and unlike others who have attempted a petrol diesel, Mazda decided to use a spark plug in each cylinder under certain conditions, primarily when the engine is cold on start-up. It’s called that spark controlled compression ignition (SCCI). Mazda says the brief transition period from spark ignition to compression ignition was tuned to be seamless.

The SkyActiv-X engine will be equipped with a supercharger and will produce 10-30% more torque than the current engine (SkyActiv-G). HCCI enables a super lean burn mode that increases engine efficiency by 20-30% over the current gasoline engine, is 35-45% more economical than Mazda’s comparable 2008 gasoline engine, and “equals or exceeds” the new diesel in terms of fuel efficiency. .

Mazda timeline for new technologies.

Mazda Timeline

The first SkyActiv-X (HCCI) engine and car will be delivered in 2019. Mazda executive vice president Akira Marumoto said Mazda has no plans to supply the engine to other automakers. At least that’s what he says today. Automakers can make a lot of money licensing technologies to others when there is only one solution to a common problem. Mitsubishi, for example, invented a balancer shaft to reduce the vibration inherent in four-cylinder engines, and most automakers have adopted it.

Mazda is also moving forward with its plans for a diesel-powered car, which has been rumored for nearly the past decade. The SkyActive-D engine is coming to the popular new Mazda CX-5 compact crossover this fall. Mazda will use it as the performance engine for the CX-5.

Separately, Mazda said it would begin testing the Mazda Co-Pilot concept by 2020 and “aims to make the system standard on all models by 2025.”

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