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Design for Fuel Efficient Piston Engines |
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Yoke Technology - Previous Attempts |
There
have been many previous attempts to utilize
the “yoke” mechanism for piston
engines. Most attempts have been met with
limited success or no success at all. And
all have failed to produce widespread application
or develop worldwide interest. Russell
Bourke's pioneering effort to incorporate
the “scotch yoke” mechanism
into the engine designs of the 1940’s
& 1950s has been the most successful
attempt to date. Bourke deserves much credit
for Fisher's “yoke-arm” technology
because the Fisher design was, in fact,
inspired by Bourke's work and his promotion
of the yoke concept for piston engines.
Bourke’s R&D efforts provided
Fisher a “bridge” to a superior
design, which now includes additional features
unknown to Bourke, and has significantly
advanced engine performance beyond even
what Fisher or Bourke was expecting. Many
will recognize Russell Bourke, and also
Collins Motor Corporation's (CMC Power Systems),
Roger Richard and others, all Bourke’s
modern day protégés, as determined
pioneers who made significant contributions
toward the advancement of piston engines.
The eventual widespread success of the Fisher
yoke-arm for piston engines and air compressors
will promote increased recognition and appreciation
for Bourke and others in their determined
pioneering efforts. It will soon be obvious
to many engine manufacturers and engine
advocates that Russell
Bourke and others understood the importance
of continuing the evolution of technology
within the Engine Industry, although Bourke
could not quite bring about the final aspects
of the needed breakthrough. Fisher has finally
completed the equation for a superior piston
engine design by discovering a new crankshaft
linkage called the yoke-arm.
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Yoke-Arm
Advantages vs. Previous Attempts
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Fisher
has added a uniquely designed “yoke-arm”
between the piston rod and crankshaft which
is patent protected, both US & foreign
(US patent no. 7,328,682). The yoke-arm is
much different than previously tried yoke
mechanisms such as, for example, the Bourke
scotch yoke or “Bourke-Cycle”
as previously discussed. The Fisher yoke-arm
(shown below), an important and integral part
of this breakthrough technology for piston
engines, provides two main advantages over
Bourke and conventional engine designs. (1)
The increased piston dwell provided by Fisher
is well beyond that possible with Bourke’s
scotch yoke and associated "harmonic
motion" for improving combustion efficiencies,
and also well beyond all attempts by others.
The Fisher yoke-arm can be designed for more
or less dwell depending on the needs of particular
applications, which is a severe constraint for
the scotch yoke. (2) In addition to increased
piston dwell, the added benefit of much less
piston friction plus the increased mechanical
advantage over conventional engines contribute
to superior gains in mechanical efficiencies
promoting even higher performance and added
fuel economy. As it turns out, there is about
a 10% mechanical advantage over the conventional
engine piston rod-crank relationship.
yoke-arm
linking crankshaft to piston rod
a device to substantially increase piston
dwell during combustion
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Where are We Now?
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Computer
modeling and performance
curves have demonstrated superior advantages
when compared to conventional engines, and
FEA testing has been completed for a very
effective yoke-arm design. Based on the
success of computer modeling and preliminary
prototype testing, a second prototype (4-stroke)
is currently under construction with dynameter
testing scheduled for completion by the
end of 3rd or 4th quarter 2009. Our development
team, which understands the benefits of
piston dwell, anticipates that 4-stroke
dyno testing will validate the superior
performance demonstrated by computer modeling,
and is expected to reconfirm the dyno test
results for an earlier 2-stroke design that
showed superior fuel economy and power increases.
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Simplicity of Design - an Important Strength
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Fisher's
yoke-arm offers new, exciting and innovative
"technological upgrades" for all
conventional piston engines. Engines that
are produced for the automotive, farming
& construction, marine, aircraft, recreational,
lawn & garden and motorcycle industries,
both gasoline and diesel, will especially
benefit to help protect our environment. Although
performance benefits are substantial, it
turns out that the conventional engine component
parts are not appreciably affected. Performance
curves derived from computer modeling
plus our preliminary dyno tests have shown
that the Fisher yoke-arm technology offers
unprecedented operational and performance
advantages never before achieved with a
single modification that offers such simplicity and
reduced cost for piston engines. An important
strength for the Fisher Technology, is the
relative ease of modifying existing engine
arrangements at the factory. Retooling by
engine manufacturers will be minimal, and
the degree of simplicity that affords such
big time performance benefits has never
before been possible.
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Advantages for Air Compressors Also
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In
addition to piston engines, efficiencies
for piston driven air compressors are also
substantially improved when using the yoke-arm
mechanism. Some of the important benefits
for compressors will be the noticeable reductions
in energy required to operate air conditioning
and refrigeration systems. Substantial increases
in mechanical efficiencies, due to significant
mechanical advantages and reduced piston
friction, greatly reduce the power requirements
for air compressor, refrigeration and heat
pump systems. Home heating and air conditioning
applications will experience noticeable
reductions in power requirements which will
reduce everyone's energy bills.
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