QUOTE(SKYjack @ Jan 14 2021, 09:59 AM)
I'm very interested to know this higher combustion efficiency by flat doom piston. Is it a Geely patent? Tq.
It is not Geely patent, it is just merely the choice for manufacturer on piston design.
Different Piston setup has its own purpose for the engine design, but flat top in general will have most even flame distribution but often not a choice for turbocharger engine because it doesn't help with reducing compression ratio to avoid knocking, which also means turbocharger that adopt flat top piston need more precise engine design to prevent knocking.
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Flat-top Pistons
As simple as it sounds, a flat-top piston has a flat top. Flat-top pistons have the smallest amount of surface space; this enables them to create the most force. This type of piston is ideal for creating efficient combustion. Flat-top pistons create the most even flame distribution. The difficulty that comes with this is that it can create too much compression for smaller combustion chambers.
Dish Pistons
Dish pistons present the least problems for engineers. That is more because of where they are used than any property they themselves hold. They are shaped just like a plate with the outer edges slightly curling up. Typically, dish pistons are used in boosted applications which do not require a high-lift camshaft or high compression ratio.
Dome Pistons
Opposite in concept to the dish pistons, these bubble in in the middle like the top of a stadium. This is done to increase the surface area available on the top of the piston. More surface area means less compression. While more compression does mean more force is generated, there is an upper limit of what each combustion chamber can handle. Reducing the compression rate in this way essentially prevents the engine from ripping itself apart. It’s just one tool in limiting the amount of force generated to what the engine is capable of handling safely.
Above are the explanations I copied from some random site that sells engine parts
This is my little research on the internet tells me, please correct me if I understand anything wrongly.