Submitted via IRC for AndyTheAbsurd
It's called Spark Controlled Compression Ignition, and Mazda made it work.
Despite rumors to the contrary, the internal combustion engine is far from dead. Recently we've seen several technological advances that will significantly boost the efficiency of gasoline-powered engines. One of these, first reported back in August 2017, is Mazda's breakthrough with compression ignition. On Tuesday, Mazda invited us to its R&D facility in California to learn more about this clever new Skyactiv-X engine, but more importantly we actually got to drive it on the road.
The idea behind Skyactiv-X is to be able to run the engine with as lean a fuel-air mixture (known as λ) as possible. Because very lean combustion is cooler than a stoichiometric reaction (where λ=1 and there is exactly enough air to completely burn each molecule of fuel but no more), less energy is wasted as heat. What's more, the exhaust gases contain fewer nasty nitrogen oxides, and the unused air gets put to work. It absorbs the combustion heat and then expands and pushes down on the piston. The result is a cleaner, more efficient, and more powerful engine. And Skyactiv-X uses a very lean mix: a λ up to 2.5.
(Score: 3, Interesting) by requerdanos on Wednesday January 31 2018, @02:01AM (3 children)
Not exactly; a key difference seems to be that in a diesel, you get enough compression to ignite first, and then after that the fuel is injected, whereas here, the fuel is injected first, just before compression.
I found the article a fascinating read; the engine is designed to have leaner fuel swirling around the outside edges of the cylinder head (to combat preignition), with ever so slightly richer fuel at the center of the cylinder head area (to be more amenable to spark ignition). The spark timing is dynamically adjusted based on feedback from pressure sensors in the cylinders themselves. Very cool engineering.
(Score: 3, Informative) by frojack on Wednesday January 31 2018, @02:18AM (2 children)
But not new.
Google Otto Cycle. Stratified charges were being done before WWII.
Further they were compressing and igniting fuel and air mixtures with spark plugs back then.
No, you are mistaken. I've always had this sig.
(Score: 3, Funny) by requerdanos on Wednesday January 31 2018, @02:36AM (1 child)
Not new, just a refinement of the "Otto Cycle" aka "Suck, Bang, Blow*" with cool engineering to get some more torque and efficiency. Helps with CAFE and fuel cost if it works out.
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* There's a biker bar near here called "Suck Bang Blow." I think that's a great name for a biker bar. I don't think The Otto Cycle would have caught on as well--less lowbrow innuendo--but who am I to judge.
(Score: 2) by insanumingenium on Wednesday January 31 2018, @04:45PM
Where's the squeeze? 3 Cycle engines, that explains the potato potato sound those Harleys make...