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Variable stroke crank shaft for an internal combustion engine

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2012. / Our planet is continuously being depleted of its natural resources leading to a need to
conserve energy and the environment. One of the major energy consumers is the
conventional internal combustion engine. Many attempts have been made to make these
conventional internal combustion engines more efficient focusing mostly on the combustion
side of the engine.
The focus of this study is on the modification of the reciprocating and rotating components of
the sub-assembly of a conventional internal combustion engine. An in-depth review was
carried out on the fundamentals of spark ignition internal combustion engines and savings on
fuel consumptions.
A prototype single piston internal combustion engine was developed that can adjust its stroke
length. Lengthening or shortening the stroke and simultaneously extending or retracting the
connecting rod's travel distance, allows the internal combustion engine to function very
efficiently consequently reducing the free space between the piston and cylinder head at
TDC position. This allows the internal combustion engine to alter its power capability on
demand whilst maintaining relatively high compression efficiency. The method of altering the stroke length is achieved by manipulating gears situated internally
and externally of the engine sub-assembly. The control of these eccentric gears lowers or
lifts the crankshaft in a radial motion. The eccentrics also control the automatic extension or
retraction of the connecting rod's travel distance.
The externally concentric gears control the mechanism that allows the internal combustion
engine to change its capacity easily as adapted for automation. This study does not extend
into the automation issues of the external mechanism.
The prototype engine that was built could not endure vigorous testing and it failed after
running for a short while. The primary focus had been on the kinematics of the engine
mechanism - and to show whether the idea was feasible. The engine passed the kinematics
test but failed possibly due to dynamic loads. Investigating this requires measuring
instantaneous temperatures from which peak pressures can be deduced. This was not done
because it was outside the scope of the project.
Date January 2012
CreatorsIsmail, Fareed
ContributorsGryzagoridis, J., Cape Peninsula University of Technology. Faculty of Engineering. Dept. of Mechanical Engineering.
PublisherCape Peninsula University of Technology
Source SetsSouth African National ETD Portal
Detected LanguageEnglish

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