A characteristic of crankshaft behavior at the initial firing stage

Abstract

The demands on a modern engine system are increasing rapidly. High performance engines, low fuel consumption, low noise and vibration are several factors that a customer demands simultaneously. These demands pressurise engineers to upgrade engine designs and require optimisation of engine components. Since the crankshaft is one of the key components in the engine system, identification of dynamic behaviour plays an important role in the design. Thus, an accurate prediction for the dynamic characteristics of the system using finite element method is essential for modern equipment. The crankshaft, supported by the crankcase bearing, receives the combustion gas force and gas torque force exerted from the pistons through the connecting rod in each cycle. These gas forces are due to the gas from the exploding fuel air mixture impinging on top of the piston surface while the gas torque is due to the gas force acting at the moment arm about the crankshaft center. Generally, the latter forces are higher and act cyclically.