The Waissi Engine

[NeilBlanchard]

This engine design replaces the crankshaft:

Now for Something Completely Different: the Waissi Engine

[Frank Lee]

I think I love it!

[darcane]

Um, so it's essentially a fancy version of a Scotch Yoke piston engine...

That was done 30+ years ago, and there are functional versions:
AutoSpeed - The SyTech Scotch Yoke Engine

[wdb]

Looks like there might be a net gain in internal friction, or perhaps it's a wash. Loss of connecting rods is countered by the mass of the cam disk thingie, so there might not be much gain there either. It seems to me that the biggest benefit is that the cam's rotating masses cancel one another, which may make for a smoother running engine. (A six cylinder version would wipe that out of course.)

[Frank Lee]

Originally Posted by darcane

Um, so it's essentially a fancy version of a Scotch Yoke piston engine...

Yeah, Scotch yokes and cam driven pistons and such have been around forever, but they suffered unacceptable friction losses and/or durability issues; I don't see that failure mode in this version.

P.S. The Sytec is neat too, but "limited" funds are the hold-up? They had over 1.5 million to spend every year for 22 years...

Actually Neil should have said this design replaces the connecting rod; it's crankshaft could still arguably be called a crankshaft but more accurately a camshaft.

[gone-ot]

One has to wonder about the *life* of those very l-o-n-g, thin, connecting rods between the piston pairs. How many tension/compression cycles can they endure before fatigue and failure happen?

[RustyLugNut]

Originally Posted by Old Tele man

One has to wonder about the *life* of those very l-o-n-g, thin, connecting rods between the piston pairs. How many tension/compression cycles can they endure before fatigue and failure happen?

A simple run through finite element analysis (FEA) would give you the major failure zones. The uploaded pictures are simply a spacial analysis model. Sytec has run an engine for 60K km. I was thinking bearing pressure zones on the cam pin would be problematical.

Performing engine design analysis for one of the AXP teams, we came to the conclusion that this engine gave little advantage other than the improved dwell time at top dead center (TDC). A long connecting rod, short throw engine could give you the same advantages albeit in a much larger package.

It is beautiful engineering though. And that I can appreciate.

[jakobnev]

What problem is this supposed to fix?

[RustyLugNut]

The fourth of the pictures shows the creative solution that Waissi has brought to the Scots yoke engine. The bearing area has been increased significantly and a large hydrodynamic area means thin oils can do the job. The large pin could house liquid bathed roller bearings.

There are some good improvements of merit in this engine.

[Frank Lee]

Originally Posted by jakobnev

What problem is this supposed to fix?

Connecting rod angularity issues and reduced piston skirt friction. Also I'd imagine the ring pack can be held more square in the bore so maybe tolerances and sealing can be tightened up. Looks like the whole engine package can also be made more compact, rigid, and light.