Redesigned "Leakproof" Elbow Engine

[Captain Jerry]

Yeah, I heard it. One of these days, after I tame the donkey, I will try my hand at an elbow.

There is no good reason to even consider an acute angle, but I actually like the oblique angle numbers. If you consider the bore/stroke ratio (10/12.3) is much closer to normal in the 135° configuration, with all of the benefit of reduced piston speed, better ring and bore wear, etc. A few years ago I built an similar engine with a 108° angle and it ran quite well in spite of my limited equipment and limited experience at the time.

It is next to impossible to experiment with the range of possible angles for an elbow type engine due to the number of parts that need to be modified. BUT! The geometry of the elbow engine is identical to that of a swash plate engine. Just imagine an invisible swashplate that is set at a 45° angle to the pistons of a 90° elbow engine at the center of each elbow.

I have done a fair amount of experimentation with that type. It is easy to change the angle of a swash plate and it can be done by changing only one simple part. I have used swash plate angles as close as 15° that correspond to a 165° elbow but I have settled on a 20° swash plate angle as a good compromise. That is not far from the 22.5° geometry of a 135° elbow.

So many options, so little time.

Jerry

 

[Noitoen]

When I said 45º, I meant bending the rods by 45º from straight like your 135º example. That's (about) the angle of many hydraulic swash plate motors/pumps. I suppose the real 45º motor you drawn, would work ok as a motor but not a pump.

 

[Noitoen]

:ideaon´t forget "spring return assist"

 

[Ken I]

Captain, Noitoen - the 135° should work - I'm pretty sure the 45° won't.

I had a brief go at modeling the friction but the maths doesn't gel.

Well after a few beers one shouldn't attempt calculus.

"DON'T DRINK AND DERIVE".

Ken

 

[steamer]

Looking at the 45 layout Ken, I think by inspection it will violate the old 2/1 rule.

If you want a derivation of the 2/1 rule and a self locking bearing I can do that.... but I'm in the throws of washing machine surgery right now....considering the quack doctor operating.....I don't have a lot of hope for the patient! :

Dave