Last October, it seems that Mazda quietly filed a patent for a twin-spark, direct injection version of the automaker's iconic rotary engine. It's taken this long for anyone to actually notice application 20090101103, which appears to have been approved just last month, but it's still an interesting development in the ongoing saga of pistonless engine.
First developed and patented by German engineer Felix Wankel way back in the early 1950s, the rotary engine has always been able to make lots of power relative to its small size, but it has also proven extremely difficult to keep emissions and fuel consumption at acceptable levels. Adding direct injection may be one effective way to manage the fuel consumption issue, and it's long been assumed Mazda would go this route on the next version of its Renesis rotary.
Further, it seems the automaker is working to slightly change the dimensions of the rotor housing (increased displacement?) and the distance between the twin spark plugs, which may have desirable effects on the engine's tailpipe emissions. It's certainly no sure-thing that this engine is going into production, but it shows the Japanese automaker is intent on improving its rotary technology. Click here to see the actual patent application, and check out all seventeen diagrams in our gallery below.