> A shorter distance that is closer to the combustion chamber increases the compression ratio because there is less space for the fuel/air mixture. When the system is operating in low compression mode the piston travels more and does not reach as high.
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.
Yes, you are correct. It was a mistake on my end. Thanks for pointing it out. I cannot update the post to fix the mistake. Hope people upvote your post to make sure it stays visible.
Erm, I'm not sure I get it. I think I'd need to see an animation. If the crankshaft is fixed I don't see how that linkage can change the stroke length because all it shows in that diagram is the piston further along the stroke, which is what all piston engines do when the crankshaft rotates.
So yeah, I probably need to see an animation to grok it.
The crankshaft is in the middle part it doesn't move in relation to the head.
The image explains is pretty well, the piston is connected to the "multi-link" which changes the angle make the piston head move further into the cylinder.
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.