Norihisa Seno

A small three-way valve using particle excitation with piezoelectric transducers for hydraulic actuators

Abstract Robots composed of hydraulic actuators have been utilized in various fields and at disaster sites. However, the hydraulic control system for multiple-degree-of-freedom mechanisms is large because such systems require many control components. The purpose of this research was to develop a small hydraulic flow control valve. This paper describes the fabrication and evaluation of a small three-way valve by particle excitation using a piezoelectric transducer. This valve consists of two transducers and can switch the inlet and outlet ports by applying an AC voltage of different driving frequencies to each transducer because each transducer has different resonant frequencies. The flow rate was controlled by applying a voltage to the piezoelectric transducer. We evaluated the vibration characteristics of the fabricated three-way valve. The vibration velocity exhibited peaks at 120 and 155 kHz for the inlet and outlet port, respectively, and that of each transducer increased with the applied voltage. Therefore, this three-way valve can switch the opening port by changing the driving frequencies and continuously controlling the flow rate. As a result, we have succeeded in driving the novel small three-way valve.

A small three-way valve for hydraulic actuators using piezoelectric transducers

Hydraulic actuators has been utilized for various types of robots. However, hydraulic control system for multiple degrees of freedom mechanisms has a large volume because such system needs many control components. The purpose of this research is to develop a small hydraulic flow control valve. In the previous research, we have developed a small flow control valve using particle excitation by a piezoelectric transducer [1], and applied this valve to a hydraulic system. In this research, we have fabricated and evaluated a small three-way valve for further miniaturization.

Micro droplet generation using micropore plates oscillated by ultrasonic torsional transducers

Monodisperse droplets have been an important subject in fields such as electronic materials, cosmetics productions and medical science. The goal of this study is to generate micro and uniform droplets in various viscosity liquids by using a micropore plate oscillated by an ultrasonic torsional transducer. When the micropore plate was not oscillated, droplets were generated irregularly. On the other hand, when the micropore plate was oscillated by the ultrasonic torsional transducer, droplets were generated regularly by ruffling liquid surface. We have generated droplets in the air by using pure water and silicone oil of various viscosities and evaluated droplets. We have designed the ultrasonic torsional transducer and a droplet generation device to apply a high pressure for the use of higher viscosity liquids. We have succeeded in generating droplets by using pure water when we used the ultrasonic torsional transducer. The average diameter of droplets was 30.0µm and the standard deviation was 0.98. We have also succeeded in generating 50cSt silicone oil droplets using the droplet generation device. The average diameter of droplets was 98.0µm and the standard deviation was 0.76.