sinple, compact linear to rotary

[fullofhotair]

This probably isn't a new idea ,but it seems like a good way to get the up and down motion of the piston going in one rotational direction .The idea is a double rack and pinion. Think of a tuning fork with one leg twice the length of the other. The short leg has teeth going up. As the piston goes up it turns the pinion gear clockwise. The pinion only has gear teeth on one half of it .As the shorter rack runs out it has turned the pinion to the point were the other longer rack grabs the gear teeth. The longer rack has its teeth facing down .So it pulls the gear down ,still clockwise. They use rack and pinion on small electric motor, so it must be pretty efficient .Ive just never seen this setup used on a piston engine and I wonder why not?

[fullofhotair]

After reconsidering the design, the two sides of the tuning fork shaped, double rack would be equal lengths. They would have to be no longer than the length of one stroke of the power piston. The pinion gear would be the flywheel. You would still use the pinion gear with only half the teeth on one side.

[jesterthought]

A wobble drive can be compact, http://en.wikipedia.org/wiki/Axial_engine . There is not the sliding friction of a cam and there is little side load from the conrods. No need for a whole disc, and a conical crank to one side is easier and less frictious than an angled "crank" through the middle.

[fullofhotair]

jesterthought,
Those options only work on multi-cylinder engines. Iam trying to find a solution for a one cylinder stirling engine.

[fullofhotair]

http://blog.dugnorth.com/2011/03/recipr ... anism.html

I found it, it works! They are using it just opposite of how I planned it. They are using a motor and turning that into reciprocating movement. Just take the picture turn it 90 degrees and add a con rod at the bottom. Too simple. Just cant see why it isn’t used on one cylinder engines?

[zhivko]

http://www.mekanizmalar.com/rack_and_pi ... ocate.html

I see one problem - this will give you non sinusoidal motion - and with heavy displacer (when it needs to reverse direction) it would cause huge forces. If you think a little bit - whole displacer mass should change direction in almost no time - that's huge acceleration and also with small mass will cause huge force.
That force will probably crush gears with high rpms...

[fullofhotair]

Zhivko,
Thank you for your response.I do see the problem now. This should still work on a low rpm engine like an LTD or would the the lack of sinusidal motion still tear at the gears to much to make it efficient?