Free Piston Engine Linear Generator / e-bike power source

Discussion in '2-Stroke Engines' started by Email, Jul 1, 2014.

  1. Email

    Email Member

  2. HeadSmess

    HeadSmess Well-Known Member

    mmmm, the free piston idea has been around since...well, ever... strapping an alternator/generator to it has been too. never caught on much :(

    i was thinking the philips mp1002ca was a free piston, but no...tis not. the use of the free piston is a lot more common in stirling engines but.

    thay have this advantage you see...they "self start". one very tricky part of a free piston, getting the initial oscillation going.

    im doing some googling now, i have to try and find a picture of the best design (in my opinion) to date... a twin cylinder free piston, ie, one at each end, running twostroke uniflow cycle, with the "crankcase" side of things being a third cylinder in the centre...hard to describe without a pic but oh so simple once seen.

    (ten minutes later, still cant find it... looked something like a cross between these ones but ;))

    (just remove the cam drum which is its method of producing rotation...basically a simple cam drive engine minus the other cylinders)

    (pretty close except the turbine bit)

    similar but the combustion chamber(s) should be at the ends of the pistons?

    (i am now sick of searching for an image that may have never been published online... i saw it in an old mechanics illustrated or summink back in B(efore)www.)

    the stirling has another long as you can heat one side doesnt MATTER WHAT YOU USE TO HEAT IT!!!! petrol, gas, diesel fuel...crude oil. dirty old diesel sump oil. focused sunlight. stored heat, be it geothermal, solar or some other type...
  3. libranskeptic

    libranskeptic Member

    The man is right.

    This is huge and ~no one seems to get it (~zip coverage of it? This story is from 2014 methinks.). Engine efficiency doubles from ~20% to over 40% and improving. That's sensational.

    All sorts of options open up re; miniaturization, simple manufacture, way fewer components, materials (ceramics?), weight, ... Its a very different paradigm for motors.

    The claims just have to be right.


    This is toyota talking. They don't come any more reputable. It's slated for the next generation of Prius already. Its real.
  4. HeadSmess

    HeadSmess Well-Known Member

    f toyota and f the prius, just a joke from the word go.

    why use "atkinson cycle" engine without actually being "atkinson cycle"?

    the way they do it, you use energy to get air INTO the cylinder, then wopo, use energy pushing it back OUT as you wait for the inlet valves to close.

    that defeats all this tech developed to enhance airflow into a timing, all that guff. filling a cylinder then pumping half of it back out again is just plain stupid. it takes energy to get it moving. halting it then pushing it the other way is just wasting energy.

    feel free to prove how that concept isnt utterly braindead :)

    then...whats with the radiator? cooling system? isnt that just a way to dump energy, excess heat? waste it? blow it out the exhaust or chimney or whatever? akin to lighting cigars with banknotes if you ask me.

    if they DO use a free piston engine, and they DO use its wasted heat to do something useful, say...peltier generation, absorbtion refrigeration (why run a compressor when you could use the dumped heat to cool the cabin?), stirling generators (a stirling can work with less than 2 degree temperature differential!) then finally, i will accept toyota's prius.

    until then, the mere sight, mention, awareness of the toyota prius makes me froth at the mouth...a joke car for joke yuppies that think drinking spring water from 70% recycled plastic bottles is being "green" and "eco friendly". suggest the idea that ALL water is and was sewerage at some point and they think youve flipped your lid...its SPRING water! they say... "ecologically harvested in an environmentally friendly manner"... forget how transpiration, evaporation and precipitation all work together in a tightly knit process. yuppies know better :)

    the they consider how environmentally damaging the batteries are as they plod along in their uber green hybrid POS??

    oh no, of course not, because its "green" and "in touch with the planet and its needs"...

    end rant :)

    mmmm, free piston stirling engine with efficiency ratings of 75% plus... it will never happen though. no interest in making things that actually make SENSE these days :)
  5. HeadSmess

    HeadSmess Well-Known Member

    heh heh heh, i think breaking my jaw and taking lots of codeine has made me more lucid :)
  6. wheelbender6

    wheelbender6 Well-Known Member

    I have seen modern engine designs that eliminate the mechanical valves, but that is the first engine I have seen without a crankshaft.
    The free piston engine looks perfect for generating electricity.
  7. HeadSmess

    HeadSmess Well-Known Member

    yep, they are. just like those shake n charge torches ;)

    they run pretty efficiently, self adjusting compression ratios, usually run at fixed speeds as a generator as the loads fairly constant.

    they vibrate like a jackhammer though... when using just single pistons/cylinders.

    starting is awkward. about the only real issue but a shot of compressed air works wonders. so much simpler than all these extranuous items required on ...grrrrr... the prius.

    dam the prius to the murky depths of the pit of brimstone! evil in disguise!
  8. butre

    butre Well-Known Member

    forget a generator, an opposed twin free piston engine would make a damn cool antilag system for a turbocharger. could run it at about a trillion rpm I imagine since you don't have to worry about rods or bearings and an opposed twin is pretty well balanced, so a pretty small one could do the job
  9. HeadSmess

    HeadSmess Well-Known Member

    the limit appears to be about 32,000 oscillations/min.

    at this point, the speed of sound takes over and the ports no longer flow anything...

    the one reason no engine other than turbines cant do much over that.

    still yet to find any "piston" engine that exceeds that dubious on some of the claims made by rc engines too ;) yet to see any that actually DO hit 30k+

    the problem with opposed pistons is that if there are no connecting rods to control the phasing, any differences in pressure, friction, etc, causes the whole system to fail.

    having two such things setup with "seesaw" links would work...

    you will find that the stirling free piston engines still use some type of spring diaphgram thingy to retain the 90degree phase required.


    stirling is the way to go though. as mentioned...ANY source of heat will work.

    one guy was doing them on model airplanes...he was pouring molten salt around the hot ends! no flames ;) big thing when your plane goes haywire and lands in someones haystack...
  10. butre

    butre Well-Known Member

    32,000 is damn close to a trillion for a piston engine. wouldn't be near as hard on the valvetrain and turbo as the typical throttle bypass method
  11. libranskeptic

    libranskeptic Member

    Being lucid got your jaw broken in the first place :).
    HeadSmess likes this.
  12. HeadSmess

    HeadSmess Well-Known Member

    HA HA!

    actually, no, i fainted and hit a concrete floor.