چكيده به لاتين
Crankshaft is one of the main parts of an engine which transforms the reciprocating motion into the rotational motion. The crankshaft is an axis with several cranks, according to the number of cylinders attached to it, and has specific three dimensional geometries which differ with each other in the number of cranks. The crankshaft discussed in this thesis has three cylinders. One of the problems of the three-cylinder engine is lack of balance. In this thesis, while studying the forces and the related moments, a method for balancing three-cylinder engines is developed. For a three cylinder engine in stable condition with 1 20º angles between the cylinders, primary and secondary rotational and reciprocating forces are self-balancing, but resulted moments are not balanced, and therefore cause noise in bearings. To eliminate this, balancing shafts are attached to the cylinder block. These shafts, along with the counterweights attached to crankshaft, cause the aforementioned moments to become balanced. Dynamic balancing of a multi-cylinder engine depends on both static and dynamic equations of rotational and reciprocating masses to be satisfied concurrently. Thus, numerical analysis of dynamic balancing on the crankshaft of the three-cylinder engine is of high importance. The crankshaft of the three-cylinder engine resembles the letter Y. Because of this shape and its geometrical property, balancing of moments resulted from forces becomes awkward, and is different from
balancing operation of a four-cylinder engine. Therefore, after studying the design and
balancing principles of a four-cylinder engine, a solution will be suggested for balancing the forces and moments exerted on the three-cylinder crankshaft.
Keywords: three cylinder crankshaft, optimized design, imbalance elimination, counterweight.
