[net.cycle] measure torque in-situ?

prins@cornell.UUCP (10/26/84)

From: prins (Jan Prins)
Is there a way to continuously transduce engine torque somewhere along the
driveline?  That information could be useful in an ignition/fuel injection
control system attempting to maximize engine output.  A long time ago I 
heard of an unlikely scheme involving a photomultiplier and a laser shining 
over a driveline component that 'bent' minutely under increasing load.

Does such a device exist?  Is it ever used to supply data to an engine
control system?  Or are the various other engine parameters (e.g. intake
air mass, air/cylinder temperature, oxygen content of exhaust, detection 
of preignition) adequate for indirect determination of output?

With such an input, a digital engine control system (e.g. Bosch Motronic) 
could lend itself very well to a bit of 'in-the-software' engine tuning 
(although you could really wreck things up!).  

Yann Prins   cornell!prins   (prins@cornell.arpa
                              prins@cornell.csnet
                              prins@crnlcs.BITNET)

fowler@uw-beaver (Rob Fowler) (10/26/84)

References:<1884@cornell.UUCP> 
Back before I confronted my own mortality I owned two BMW's, a '68 R69S with
police electrics and a R75S.  As I recall, both of these (maybe it was my
CB450) had a shock absorbing/torque averaging element in the drive train.
This consisted of a circular carrier on one shaft that had rollers that
engaged some cams (arranged in a circle).  The rollers ran up the cams
against spring pressure.  some spring tensioned rollers that ran up on a
circular cam as the torque increased.  You could monitor the torque
mechanically by measuring the mean axial displacement of the roller carrier.
What I don't remember (actually never knew) or whether this thing ever really
did anything or whether it's yet (AFTERBURNERS ON!) another German 
engineering monstrosity.

The last comment reflects my belief that the guys who engineer motorcycles,
even in Germany,  all flunked out of engineering school.  The only thing
that saves BMW's is the fact that the fine workmanship compensates for the
atrocities to good taste and economics committed by the engineers.  Fer
instance, the R69S was a factory hot rod for European and American kids.  It
was based on the R60. It had no oil pump, only slingers.  The resulting lack
of lubrication meant that it had to use roller/needle bearings everywhere
including the rocker arms.  The high compression pistons kept blowing off
the heads so they added a couple more bolts in areas that aren't really strong
enough.  Finally, all the added torque would cause the engine to self
destruct due to crankshaft flex.  Solution?  Use self-aligning roller
bearings on the crank so flex won't wreck them.  What a sleazy and expensive
hack!!  Fortunately, almost nothing wears out.  Unfortunately, I bought the
bike as a basket case and every trip down to the shop was an expensive piece
of my education.

Actually, the R69S was just a stop-gap until they could get the newer series
out.  All the engine problems were fixed.  It still depended on very precise
machining and assembly in such areas as the transmission output shaft.  This
little gem contains an anti-asphalt rash device in the form of mounting the
universal joint on a tapered shaft that is pressed into a matching component
in the transmission.  The idea is that this thing holds by friction but if
the engine should seize up the joint would break, thereby keeping you from
locking the rear wheel and dumping.  It depends on the quality of those
mating surfaces, good metalurgy to keep the surfaces from bonding to each
other, and the care taken in pressing the pieces together (by inserting a
bolt, torqing it "just so", and then putting the bolt back wherever it
belonged elsewhere on the bike).  The result of all this is that you
shouldn't push start a BMW and  you shouldn't "bump" the engine to get it
going again if it managed to die while you're reaching for the fuel cock,
at least not unless you're willing to do some esoteric roadside repairs.
The other problem is that normal changes in engine torque are enough to dump
you in a fast turn and in really heavy acceleration/deceleration a slightly
mistimed shift (I said I was confronting mortality) can "chirp" the tire.
This particular feature is therefore not likely to save if you anyway.

All this is not to be interpreted as meaning that Beemers are mechanical
crap, merely that all that keeps them from being crap is the workmanship
and that's really good.  The Japanese bikes that I owned before I got the
Beemers had both bizarre engineering and bad workmanship.
If I get back into it my next bike will be a Ural with a snowtire on
the (driven) sidecar wheel.

-- Rob Fowler

faunt@saturn.UUCP (Doug Faunt) (10/29/84)

I have seldom seen so much misinformation in one place before.
Are you running for political office?
-- 
	...!hplabs!faunt	faunt%hplabs@csnet-relay
HP is in no way responsible for anything I say here.
In fact, it may have been generated by a noisy 'phone line.
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