An interesting development currently under discussion on the wastewatts yahoo group - comments would be most welcome:-
--- > Ken Boak wrote:
>List,
> >
> >These compact, vibration free diesel engines may herald a new market for
> >diesel motorbikes, hybrid cars, outboard motors and generators. > >
> >
formatting link
>
> >Characterised by twin crankshafts geared together, and twin
> >con-rods, they are particularly low in vibration. This is almost like
> >the rhombic drive developed for the Philips Stirling engines.
> >
> >Could this be the diesel technology for the future?
> >
> >
> >Ken
>
> The first issue I see with this engine is that it can not be vibration free
> with a large reciprocating mass -- i.e. the piston(s) and connecting rods. >
> Had they built a horizontally opposed twin, I would have believed it. >
> On the other hand, it does show some interesting advantages: There is
> little uncanceled crankshaft vibration, but there is still vibration to
> pound on the bearings. It has counter rotating output shafts -- a BIG
> advantage in many applications and a way to cancel some torque loads. It
> is built using more modern techniques -- both for good and ill.
>
> Will it work? I think so.
>
> Is it smoke and mirrors? Maybe in part.
>
> Dave 8{)
It is my understanding (but bear in mind I am no expert) that the primary out of balance forces can be 100% corrected by simple bob weights on the crankshafts. While the twinned con rods, always swinging in opposite directions at the same angular velocity, avaiod any secondary forces.
That said, Fred Lanchester's version was indeed a flat twin (and later ISTR a four) while the rhombic drive stirling of course has the displacer moving in opposition to the power piston.
I guess this is all drifting a bit OT. I will post the link to uk.rec.engines.stationary newsgroup to see what opinion is there.
Nick H.