3 ms·

The wikipedia page is quite in depth [0] but is quite dense and took me a few goes to understand. They're fascinating to understand, and they really are mechani

The wikipedia page is quite in depth [0] but is quite dense and took me a few goes to understand. They're fascinating to understand, and they really are mechanically simpler than a standard ICE + gearbox drive line. I got nerd sniped one day figuring out how my Toyota Crown "gearbox" worked only to discover it doesn't really have one. They don't even have a real neutral gear, the wheels are always mechanically linked to the engine. They require much more active computer control to work though so they aren't logically simpler in my opinion, but mechanical simplicity is what makes the biggest difference. There are certainly better more approachable sources though so I leave this as an option as the info is there, but can take a moment to understand. [0] https://en.m.wikipedia.org/wiki/Hybrid_Synergy_Drive https://en.m.wikipedia.org/wiki/Hybrid_Synergy_Drive

jgilias 2y ago
I’m with you in general. Though, with the amount of electronics and “computer-complexity” that modern ICE cars have, I’m not sure there’s a meaningful difference!
Gibbon1 2y ago
The way I think of it comes from the old ME degree I got. You can analyze assemblies by the number of degrees of freedom. Three degrees of freedom, like three linkages pinned at the corners is a triangle and the relative positions of each element are fixed. Four axis, like a square pinned at the corners if you know the relative position of two elements you know the position of the others. This is the basis for most traditional machines. Five axis is floppy. And usually avoided traditionally. The synergy drive is a five axis machine mechanically. But has two electric motor generators. By varying the speed of the motors you can control the gear ratio of the mechanical path. Since the motor speeds are indignantly variable so is the mechanical path. You end up with continuously variable transmission with a mechanical power path and an electric one in parallel. And it doesn't suck like pure mechanical ones. Totally genius.

jgilias 2y ago

I’m with you in general. Though, with the amount of electronics and “computer-complexity” that modern ICE cars have, I’m not sure there’s a meaningful difference!

Gibbon1 2y ago

The way I think of it comes from the old ME degree I got. You can analyze assemblies by the number of degrees of freedom. Three degrees of freedom, like three linkages pinned at the corners is a triangle and the relative positions of each element are fixed. Four axis, like a square pinned at the corners if you know the relative position of two elements you know the position of the others. This is the basis for most traditional machines. Five axis is floppy. And usually avoided traditionally. The synergy drive is a five axis machine mechanically. But has two electric motor generators. By varying the speed of the motors you can control the gear ratio of the mechanical path. Since the motor speeds are indignantly variable so is the mechanical path. You end up with continuously variable transmission with a mechanical power path and an electric one in parallel. And it doesn't suck like pure mechanical ones. Totally genius.