弁体をもたない液体バルブの開発

（方向制御弁の試作）

抄録

A directional control valve without a conventional valving element was developed by exploiting the viscosity-temperature dependency of hydraulic oil. The proposed valve consisted of two valving element-free sub-valves, previously developed, which were interconnected to form a branched flow path. The temperature of each sub-valve was independently controlled using Peltier modules, thereby modulating the oil viscosity and regulating flow distribution. The performance of three types of valves was experimentally evaluated under both single and multiple consecutive directional control operations. When one valve body was cooled, the flow rate in the corresponding flow path decreased and, in some cases, ceased entirely, while flow was sustained in the alternate path. Subsequent heating of the cooled valve body restored the flow rate to its initial level. This alternating behavior enabled directional control of the flow without the use of mechanical valving elements. The results further indicate that the heating temperature exerted no significant influence on the valve performance within the tested range. These findings demonstrate that cyclic thermal modulation can effectively realize a novel, non-mechanical directional control mechanism.