06/26/2003
In the early thirties, Waukeeshaw Motors patented a unique, variable
compression ratio engine.  Its been discussed hear before - but to catch you
up.

Picture a normal ricardo turbulent head side valve engine.  Place the plug
in-between the two valves and above them.  Normal so far.

Now, at the other side of the head, in the quench area, centered, at the
cylinder edge, insert another plug.

Call this the variable compression/knock plug.

The entire key to dynamic variable compression is the quench plug.  Fired some
distance prior to tdc, it will create a pocket of exhaust gas.  As the piston
closes to within .100 inches of tdc, it will quench the flame out.  The piston
closely slaps the head and starts downward.

The normal combustion has started on the other side of the chamber and
proceeds normally.  As the flame front expands to the other side, instead of
finally consuming late and of little value a fresh charge, the flame will run
into the pocket of dead exhaust gas.  In cylinder EGR. Without contamination
of the fresh charge.  By varying the timing of the quench plug, we can vary
the size of the puddle of in cylinder EGR.  Vary by the knock sensor and viola
- instantaneous active knock control.  Bring on the boost!!!!

What's the real underlaying mechanism?  Variable compression ratio.  From 500
rankine average atmospheric temperature to 4500+ rankine combustion
temperature, we get a nine to one expansion.  

By preburning a chunk of end gas, I can under control, change the volume of
the charge gas in the cylinder. If I burn 11% of the charge early, that eleven
to 12 percent will expand about 9 times and effectively double my compression
of the remainder of the charge to a 12:1 compression.  Any problems with BSFC
on 12 to 1 or higher compression?

But I've "wasted" that percent of the charge - right?  Yup - burnt up end gas
that probably would not have created pressure because the piston was close to
the exhaust valve opening or past it.  Really wasted it.

And, Since its at the opposite side of the chamber - its violent expansion
will drive the charge across the piston top into the turbulent area radically
faster than the pistons motion itself will do.  So we get verrah nicely
increased turbulence in the chamber and much quicker main charge combustion.

So know our peak pressure is increased radically to that of a high compression
engine, yet our piston motion and expansion is of a low compression engine -
so we get lots of extra time near tdc.  And that wasted gas? Its radically
increased the pressure and its doing its share.

And we've reduced the knock considerably.

By careful control, it should be possible to stay near the knock limit near
constant volume combustion thru most of the power band and load - running
knock limited combustion with all the thermodynamic advantages of a low
compression engine.

Drilling a hole in a flat head ain't a biggee.  

A knock sensor varying the timing of the quench plug - and I get both active
knock control and variable compression ratio.

And the larger the charge I burn before being quenched out, the earlier the
main charge gets quenched and the less likely the knock - so the higher the
effective compression.

And someone thought I'd give up the advantages of BFSC at high compression?