Abstract
Formerly, torsional vibration of crankshaft in off-highway diesel engine (agricultural machinery) were given little attention at their developmental stages, however with increasing agricultural activities, numerous torsional vibration problems have been noted to occur in agricultural machinery, especially in their diesel engines. This results in engine vibration, crankshaft failure and undesirable engine noise. In this paper, a six-cylinder four-stroke inline diesel engine’s crankshaft model was developed using AVL Excite Designer. After experimentally validating the model, it was used to numerically determine the torsional vibrations of a crankshaft. For the reduction of torsional vibration, two methods of crankshaft improvements were proposed based on simulation results. The first method, is to decrease the inertia of the crank pulley while the second, involves the replacement of the crank pulley with a torsional vibration damper. To ensure minimal engine alterations and cost effectiveness, the second improvement method was adopted for improving torsional vibration. Afterwards, engine radiating noise and surface vibration measurements were conducted to ensure that the required limits were achieved by the improved engine. The simulation, experiment and the improvement process of the crankshaft torsional vibration are documented further in this research. These improvements have applicable values in the developmental or quality enhancement stage of diesel engines used in agricultural machinery.
Highlights
As a special form of vibration, torsional vibrations are usually used to describe torsional deformation movements of rotating shafts [1, 2], as in internal combustion (IC) engine crankshaft
Internal and external causes of crankshaft torsional vibrations are due to elastic deformations of the crankshaft body and the periodic effect of torques acting on the crankshaft respectively
With little attention given to torsional vibrations at the developmental stages of off-highway Diesel Engine, several torsional vibration problems such as crankshaft failure, flywheel bolt failure, bearing bush pitting, increasing knock noises of timing gear, decreasing engine power and others [3,4,5], occurs commonly during operations
Summary
As a special form of vibration, torsional vibrations are usually used to describe torsional deformation movements of rotating shafts [1, 2], as in internal combustion (IC) engine crankshaft. Causes of IC engine crankshaft torsional vibration can be categorized in two-fold (i.e. internal and external causes). Internal and external causes of crankshaft torsional vibrations are due to elastic deformations of the crankshaft body and the periodic effect of torques acting on the crankshaft respectively. Crankshaft’s torsional vibration can be defined as the elastic torsional deformations caused by the periodic acting excitation torques on the crankshaft during operations. RESEARCH ON TORSIONAL VIBRATION REDUCTION OF CRANKSHAFT IN OFF-ROAD DIESEL ENGINE BY SIMULATION AND EXPERIMENT.
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