大型車用エアオーバハイドロリックブレーキシステムの解析

抄録

The Intelligent Transport System (ITS), a worldwide research project, is now in progress in many countries. Speed control of the vehicle is one of the key technologies in this research project. Deceleration of vehicles is mainly controlled by brake systems. Air Over Hydraulic (AOH) brake system consists of air tanks, a brake valve (pressure control valve with a brake pedal), transducers, wheel cylinders and pistons, and pneumatic and hydraulic conduits. This system features strong braking force owing to the pneumatic power source and quick response of the hydraulic system, so it is a popular brake system for heavy-duty vehicles in Japan. Because of the compressibility of air, the transient characteristics of the brake pressure are obviously different from those of the passenger cars. Therefore, it is necessary to investigate the transient characteristics of the brake system, so as to develop a speed control system for automated driving of heavy-duty vehicles. The purpose of this study is to investigate the transient phenomena of the AOH brake system, to evaluate the appropriateness of the simulation model, and to reveal the main factor which results in the transient phenomena. By the comparison of simulation and experimental results, the following results have been obtained in the analysis of the transient characteristics of AOH brake system.·A mathematical model to analyze the AOH brake system has been proposed and validated.·It became clear that the transient characteristics of the AOH brake system are subject to the compressibility of air, and the inertia and viscous friction of brake oil in part of hydraulic conduits.