Single cylinder Ringbom Stirling Engine
or
Hybrid Stirling engine
Did you hear these names ever?
I'm pretty shure you heard the Ringbom as a type of the Stirling family,
but what that means single cylinder Ringbom or the Hybrid in the name?
First step first.
What is the real Ringbom type engine?
The ringbom Stirling engine has a free displacer with no connection rod to the crankshaft.
Ossian Ringbom patented in 1905.
When the pressure increase the rod lift up the displacer and the gas goes to the hot side.
It's push the power piston and the cycle started. When the pressure drop because the power piston moves to the other end via flywheel, the displacer's rod turn back and the whole gas goes to the cold side etc...etc...
That displacer rod works outside of the cylinder.
So the pressure on the outer side always 1 bar.
The configuration is Gamma.
They called it hybrid because the working method somewhere between the full kinematic
and the totally free Stirling engines.
But what about the single cylinder one?
It is a modern engine where the power piston works inline with the power piston.
Typically we call this Stirling configurations as Beta.
The sealed displacer moves on a thicker rod in the cylinder under the power piston.
Another configuration the displacer fixed on this rod and moves together,
usually across the power piston.
The modern people call it free piston Stirling engine
but the totally free psiton Stirling engines are essentially a constant frequency machine.
The displacer drive system (rod area and external spring) operate at resonance.
If the load change than the amplitude change but the frequency stable as possible.
With crank in a hybrid machine the piston amplitude is constant but the frequency is changeable.
The Ringboms could start in both directions with same speed.
The displacer piston's movement create a different mode in the Stirling cycle because the displacer moves with a flattened sinus wave.
It is called overdriven mode.
It means knok to the ends and still there a bit.
