Mass Balancing of 3-Cylinder and 4-Cylinder Inline Engines with Balancer Shafts using Bond Graph Approach

Abstract

The internal combustion engines are widely used as a source of power generation in automobiles. These engines are subjected to noise, vibrations and harshness (NVH) due to unbalanced inertia forces and moments. To minimize the unbalance, various engine configurations are analyzed for the unbalanced forces and moments. Any unbalance within an engine can result in component fatigue, excessive vibration, and residual noise especially at higher engine speeds. Engines of trucks and buses develop high inertia forces which make it more essential that engine is well balanced. A well-balanced engine is more durable and operates smoothly with increases ride comfort for driver and passengers. In this thesis report, mass balancing of 3-cylinder and 4-cylinder inline engines is studied and counterweights of crankshaft and balancing masses of balancer shafts are designed in order to neutralize these inertia forces and moments developed in the engine and to make the engine well balanced as a whole. Bond graph approach is utilized for modelling of engine balancing. First, 3-cylinder inline engine is modelled, further balancer shaft model has been developed and attached to main engine model. Results from simulation shows that with the introduction of balancer shaft, the engine gets balanced i.e. rocking couple of engine disappears. Going further, two balancer shafts have been modelled and are integrated with the 4-cylinder inline engine model. The simulation results are validated with theoretical results.