A Characteristic Parameter to Estimate the Optimum Counterweight Mass of Symmetric In-Line Engines

Abstract

Dimensionless relationships that estimate the maximum bearing load of two symmetric in-line engines have been developed. These relationships were empirically determined by averaging the maximum bearing loads of several engine configurations with various geometric and operating parameters. It has been found that the maximum bearing load initially decreases with engine speed, reaches a minimum, and then increases quickly with engine speed. This minimum reflects a transition speed at which the contribution of the inertia force overcomes the contribution of the maximum pressure force to the maximum bearing load. The transition speed increases with an increase of counterweight mass and is a function of the geometric parameters and operating conditions of the engine. Rapid estimation of the main bearing loads is made possible by the use of the dimensionless relationships developed in the paper.