Honda's variable stroke length engine
 

Saw this at the SAE World Congress this week and thought it was pretty cool. Sorry for the crap pics, only had the cell phone with me.

By incorporating an additional linkage onto the bottom end of the connecting rod they can effectively lengthen only the expansion and exhaust strokes of the engine cycle. In essence they reduce the pumping losses of the engine and are able to convert more gas pressure into useable work during the expansion stroke. A claimed 20% improvement in fuel consumption. I was told this technology WILL be coming to their small engine lineup eventually (mowers, generators, etc) but nothing for autos - yet.

http://i287.photobucket.com/albums/l...z/DSC00376.jpg

http://i287.photobucket.com/albums/l...z/DSC00377.jpg

http://i287.photobucket.com/albums/l...z/DSC00378.jpg

Heres a low res video of it in action:
http://www.youtube.com/watch?v=fm7omxr2Ljk

Oh, whoops, cut of the y-axis label on the "fuel efficiency" figure. It was "BSFC".

Thats really interesting thanks Deezler!

Much smarter application of atkinson than previous cranks.

Since its not good for autos(as they say?) its probably not good for varying loads. lawn mowers and generators run at more or less constant rpm and load(generators less so than lawn mowers).

It sounds like the system could possibly have trouble at high rpm(again generators and lawn mowers usually stay somewhat low). High end gens run at 1800(stand-alone units) which is not low for us but its low for everyone else.

Thanks for posting those pics! We already had a thread going on this engine, so I'm going to move these posts over there.

Whoops - this isn't what I thought it was. The other thread is about Honda's "variable piston height" (variable displacement) mod, which they also presented at SAE.

Honda (?) Variable Stroke - the way forward for sure....
 

This is the only way left for the Internal Combustion Engine - suck in 100cc, expand it through 150cc and extract all that heat which happily escapes out from our cherry-red exhaust pipes (about 40% of the fuel input energy in fact) - but not ALL is recoverable as Thermodynamics students know !

I too have a hybrid engine which uses the variable stroke idea as this Honda prototype (but mine a lot more mechanically elegant I hope !?)

Would welcome any comments: see it revealed at mecxic.com

...once you're obtained a patent (for your legal protection), please post it here for us to look over...I'm sure many of us would like to know 'how' all these different variable-displacement engines compare.

Patents are for selfish stupid little people, and for corporations to keep good ideas out of circulation. Feel free to discuss whatever you like here as long, as it is sound in theory and you aren't scamming or collecting on half baked notions.

...Patents are also for people who wish to make money from their ideas and inventions in the greedy corporate world, ie: keeping the 'honest' people 'honest' (to a degree).