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IMHO mild electric hybrids, or full serial electric hybrids would be a more elegant solution - only run the combustion engine when full power is needed, and use the electric motor otherwise. "full power" could be used to top the battery if it's not all required for motion.
Any way to know how they accomplish the variable compression?
https://www.google.com/patents/US7165517
Most engines already have knock sensors. They're used to adjust fuel/air ratio and spark timing to just above/after where the engine starts to knock. A few engines adjust valve timing while running, which is also complex mechanically, but not as difficult as adjusting compression. Now there's another variable to tweak.
It may take a machine learning system to tune such an engine. All those interdependent variables to adjust make that a hard problem. Different values required based on engine speed, load, temperature, fuel consumption, and emissions outputs. All this is usually expressed as precomputed tables which are interpolated within the engine controller. Those tables have to be developed somehow.
This looks cool, but complicated. The problem addressed seems to be that turbocharged (and supercharged) engines are sub-optimal at lower powers. IMHO mild electric hybrids, or full serial electric hybrids would be a more elegant solution - only run the combustion engine when full power is needed, and use the electric motor otherwise. "full power" could be used to top the battery if it's not all required for motion.
How are they preventing engine knock ? At 14:1 compression you'd have to be running premium gas, which would pretty much cancel the efficiency saving, in a $$ perspective.
Here is a simple explanation gathered from this image http://o.aolcdn.com/hss/storage/midas/de3e84cf46030cd7b3ea39... : The difference from a conventional engine is that the engine stroke is increased or decreased automatically. The stroke is the distance the piston travels up and down in order to turn the crankshaft. A shorter distance that is closer to the combustion chamber increases the compression ratio because…
Let's also recognize that shortblock costs will be much, much higher with this design when you need a rebuild. Many engine builders won't touch this, and I'd suspect the Nissan OEMs will say that these engine shortblocks are "factory replaceable only". Who is going to make aftermarket bearings for the multilink setup? How does the engine operate under actuator failure?
Here is a simple explanation gathered from this image http://o.aolcdn.com/hss/storage/midas/de3e84cf46030cd7b3ea39... : The difference from a conventional engine is that the engine stroke is increased or decreased automatically. The stroke is the distance the piston travels up and down in order to turn the crankshaft. A shorter distance that is closer to the combustion chamber increases the compression ratio because…
I think this is partly inaccurate. The images show the piston at the top of the stroke; when the compression ratio is high the piston is higher at the top of the stroke. But the bottom of the stroke is the same in both cases. That means the actual length of the stroke--the distance the piston travels--is greater in high compression mode. This is consistent with the definition of compression ratio, which is the ratio of cylinder volume at bottom of stroke vs. top of stroke; a larger compression ratio means a larger difference between these volumes, i.e., a longer piston stroke to get the piston higher (closer to the top of the cylinder) at the top of the stroke.
This looks cool, but complicated. The problem addressed seems to be that turbocharged (and supercharged) engines are sub-optimal at lower powers. IMHO mild electric hybrids, or full serial electric hybrids would be a more elegant solution - only run the combustion engine when full power is needed, and use the electric motor otherwise. "full power" could be used to top the battery if it's not all required for motion.
Would an electrically powered, computer-controlled turbo be silly?
Despite claiming they could replace diesels, I don't see any real numbers other than comparisons with their own gasoline engines. For internal combustion engines, the most efficent are still two-stroke diesels, which can have thermal efficiencies of over 50%: https://en.wikipedia.org/wiki/Brake_specific_fuel_consumptio... Seeing as this design includes several more moving parts than conventional ones, it's an open qu…
This looks cool, but complicated. The problem addressed seems to be that turbocharged (and supercharged) engines are sub-optimal at lower powers. IMHO mild electric hybrids, or full serial electric hybrids would be a more elegant solution - only run the combustion engine when full power is needed, and use the electric motor otherwise. "full power" could be used to top the battery if it's not all required for motion.