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In 1995,
Automotive Mechanical Engineer, Brad
Howell-Smith was researching the
internal combustion engine and its
efficiency and losses. He found that if
a typical engine’s Mean Effective
Pressure map from the combustion cycle
was simulated against a conventional
crankshaft device, that the efficiency
of that device was only 65% efficient.
For an example,
at 20-40 degrees After Top Dead Centre
(ATDC) when the pressure in the cylinder
is at its highest, a crankshaft
connecting rod
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arrangement
provides low mechanical transfer to
rotational force.
Most of the force
is applied downwards on the main
journals and is wasted as a mechanical
loss. At between 70-80 degrees ATDC, the
crankshaft mechanical device has high
efficiency because the connecting rod is
around 90 degrees to the crank.
At the
crankshaft’s point of highest
efficiency, the piston has travelled
approximately 40% down the stroke, and
the pressure in the cylinder is around
half of peak.
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