Mazda Patents Six-Stroke Gas Engine
looorg writes:
https://carbuzz.com/mazda-6-stroke-hydrogen-combustion-engine/
This time, though, Mazda has outdone itself. The company just obtained a patent for a six stroke engine. What does it do with the extra strokes, you're wondering? It separates the hydrogen and carbon in gasoline so it can burn just the hydrogen, thus taking the carbon out of the system. Easy, right? No, not easy. And it gets even wilder from there.
It works like this: The engine makes hydrogen from gasoline using its own heat and a catalyst. It then burns that hydrogen and stores the carbon to be removed later. The result is that you can burn gasoline with zero CO2, at least most of the time.
The patent is called "fuel reforming system for vehicle," which does almost nothing to describe the magic going on here. Mazda's engineers describe it as a way to recover carbon, improve thermal efficiency, and give you a car that runs carbon-neutral.
The engine only stores small amounts of hydrogen, so it doesn't need complex tanks. If there isn't enough hydrogen ready for use, it can just run the old-fashioned way on gasoline until hydrogen is ready. It could save the internal combustion engine from eventual extinction, but there's just one problem. This is pretty much the most complex solution from Mazda we've ever seen. And that's saying something.
A normal engine works like this: In cycle one (aka the intake stroke), air is pulled in on a piston down stroke, and fuel is added. Cycle two (compression stroke) sees the piston move up, compressing the mix so that the spark plug can ignite it and push it down (the power stroke) through cycle three. Cycle four, the exhaust stroke, pushes out the exhaust gases as the piston moves up. And the process repeats from there.
This engine has those four, with some changes, and two extras. On the first cycle, air is pulled like normal. It can also open an exhaust valve to pull exhaust air in, for simpler EGR.
The next two cycles are standard - compression followed by power. Cycle four is called the re-compression stroke. In this cycle, the exhaust air is pushed out through a different valve. This valve routes the exhaust air through what's called a decomposer.
Mazda's decomposer is like a catalytic converter without expensive metals. Right in front of it is a fuel injector that squirts gasoline into the hot exhaust air.
The hot exhaust and fuel mixture enters the reformer and the carbon - pure carbon, it's not CO2 yet - sticks to the catalyst. Gasoline is a mix of hydrocarbons like octane (C8H18). The reformer separates and stores both.
A carbon recovery unit holds the carbon that comes out of the reaction. It would be emptied or removed when you go in for service. The carbon that comes out can be used in steel or for pigments (and other uses) or simply stored.
Cycle five, the re-expansion cycle, pulls the remaining air back into the cylinder. Then it's pushed out through the exhaust valve in cycle six, which is cycle four in a normal engine.
Mazda's patent includes some variations. Two of them use slightly different methods in the catalyst, and one uses a four-stroke cycle where the fourth is a "scavenging cycle" that has the intake, exhaust, and reformer valves all open at the same time. Think of it like an even more complex two-stroke engine.
The idea is amazing, and certainly interesting. But the implementation is a nightmare, and its actual efficiency is questionable. In other words, it's perfect for Mazda, so perhaps we'll see some sort of production version in the years to come.
Read more of this story at SoylentNews.