Research on Extended Expansion General-Purpose Engine - Characteristic of Vibration -

The purpose of this paper is to clarify the vibration properties of the extended expansion engine with a multiple linkage system.

The mass systems were used to obtain a substitution for the center of gravity of each component part in order to formulate the movement of the multiple linkages. Attention was focused on the maximum value for the summation of inertia forces generated by the component parts of the linkages as an indicator to use in evaluating the vibration properties of the multiple linkage system. In order to minimize this value, the optimum weight of the crankshaft counterweight and its position of gravity center were examined. The calculated results of these indicators show that the maximum value for the summation of inertia forces in the previously proposed engine is 35% larger than the value in an existing engine of the same power. In addition, operation of the test engine at 3000 rpm with no load showed that the maximum scalar quantity of biplane vibrational acceleration was 2.4 times larger than the existing engine. When we analyze it about increase of engine vibration, for the characteristics that the expansion stroke gets longer for the high expansion ratio, and the expansion term gets short, we found that it was the main factor that the maximum acceleration of the piston is 2.7 times greater than the existing engine.