A Technical Interlude

I thought to take a break from the Stirling Model Saga and put forward an idea I've been playing around with since I started this steam engine thing, the rotary valve. The current incarnation of this idea is what the video is about.

I've always disliked the concept of reciprocation. Whether it's quid pro quo or the internal combustion engine, reciprocating bodies always seem so inelegant. Better to think that what goes around comes around. That's more my style. Laissez les bon temps rouler! I mean don't get me wrong, I like rocker arms as much as the next guy, especially really big ones, but they seem a bit primitive. Some guys fall for the roar of a big V8 humming at 4k rpm. I only hear the rattle of a thousand little bits shaking themselves loose as they suck energy out of the system. Now the high pitched whine of a gas turbine, Mmmmm-mm. Yummy! Pass the exhaust though a heat exchanger and use the waste heat to run an ammonia chiller and I'm orgasmic! Well, for now I must content myself with pistons for my engine, but that doesn't mean that I need to have everything reciprocating.

The design that you all saw in the last movie I posted had not only 6 cylinders and pistons, but each cylinder had its own valve that controls the timing of the steam going in and out of the cylinder. On top of that, each valve was to be connected to a Stevenson linkage in a circular configuration that would work to reverse the engine as needed. Not only is that a whole lot of fiddly bits to make, but each is another point of failure. And not failure as in stall out, or even grind to a stop. No, a failure of any of those little parts would be catastrophic, as in instant seizure followed by an explosion of 350 degree steam right into the passenger area.

So I'm thinking that's not so good. I mean, think of the screaming. It would be a major bother. I would probably have to feign some kind of concern and sympathy for the vict.. I mean passengers, and you know how exhausting that is. It would be a major buzz kill. Besides, what if that steam should just happen to be directed at one of the coolers. The steam might flip open the lid, melt the ice and warm the beer. Not a show stopper, but since I'd be stranded in the middle of whatever body of water I'd happen to have been traversing, it would be nice to have a cold one to pass the time until I drifted into land or drowned. It would be a drag.

So in the interest of a refreshing beverage, I came up with the gizmo in the video. If you want to put it in relation to the last video, imagine the above to be in the front and center of the engine. Blah blah blah. I just deleted a long winded explanation of how the thing works. For those of you interested, watch the video, and heres a picture of the control disk. If you're really interested in how it works, let me know and I'll put it in the comments. Otherwise, let it suffice to say that this valve gets rid of a lot of hassle and a lot of the little bitty parts and makes me feel a little more at ease about placing my coolers close to the engine.

This arraingement doesn't have a provision for reversing built in so I thought I would build a seperate valve that would redirect the steam and exhaust to alternate ports. I'm also toying with the idea of tapering the delivery arc to correspond to their angular position in the power cycle so that they only have a full pipe of steam from say 80 to 100 degrees on the stroke. I would like to leave the exhaust arc fully open throughout the stroke but as the reversing valve could send it to either arc depending on intent, both arc would need the taper.

If any of you are experienced steam enthusiasts, or are just some smarty pants and can think of a reason this wouldn't work, please let me know. It would be a major drag to go through the motions of building this thing only to have to rip it out and put together a more conventional design.