The Stelzer Engine

Folks,

What do you think of this free-piston two stroke engine, the Stelzer-Engine?

It can be viewed at the following site;
http://mainland.cctt.org/istf2002/components/one.asp

The reason I ask this is, I had some exposure to the engine some years ago. I believed then, that the failure of the engine was the inability to control the compression ratio and thus the effeciency. I guess this is the case with all free piston engines. I did beleive though that if one could accurately control the load then it may be possible to control the compression ration, even allowing a higher CR at higher speeds. There was also a problem with the loading in one direction been greater than in the other, i.e. the when used as a pump the discharge load would be higher than the suction stroke. This would result in different compression ratios on both sides.

The main selling points were low mechanical friction losses and cheap production costs.

Any comments,

Speedy

Re: the Stelzer-Engine

ok, it is a cute way to burn fuel- how do you harness the power? I've seen something like this proposed to generate electricity- it would drive a linear motor/generator of some sort. Might be good for stationary power or for a series hybred electric car.
The writer(s) seem to be infatuated with two-strokes. Also, this is a High School project, so I'm a bit sceptical- the 'smart plugs' touted there seem a bit suspicious.
More snake oil?
everyone?

Jay Maechtlen

Certainly doesn't look emissions friendly. Or even have good longevity. Reasons:
1) How are they planning on oiling this without contaminating the fuel and burning off a whole lot of oil (unless you're adding an oil that is emissions friendly when burnt?)
2) With the open ends, you're going to get a boatload of dirt/dust/etc on the end of the piston, especially if its got oil on it... I can't see that as being good.
3) If you close off the end, you would be compressing the air at the end, unless you put some large tanks on it. If you connected the ends together, that would seem to be better, but you'd still have to deal with the extra pressures of blowby (or would that even be a badthing? If one piston is moving 1 way, the other is moving the other way, so the only extra loss would be moving more a bit more air?)


What is interesting is that it seems that sizing the middle portion could be an effective way to add a sort of boost to the other piston (if the middle chamber is 4x the size of each cylinder (disregarding the space the rod/middle_piston take up) then you would have boost). That would, of course, depend on the timing of that plug.

All in all, it looks inefficient and possibly unreliable.


-=Whittey=-

(Oh, and the kid has 4-stroke and 2-stroke backwards at the end of the first paragraph)