In hydraulic oil circuits flow is often and inevitably accompanied by a local temperature gradient. Since the viscosity of oil varies substantially with temperature, the temperature gradient cannot help affecting the flow pattern and even heat transfer. In spite of its importance for designing hydraulic oil circuits, however, this phenomenon has not been paid enough attention to. The present paper deals with analyzing oil flow between two parallel plane walls having temperatures different from each other and also the oil. The velocity and temperature distributions in the flow were computed and compared with experimental data, showing good agreements between the two. The occurrence of natural convection was experimentally confirmed in very slow flow between the plates with lower temperatures than the oil. It was also made clear that heat transfer in laminar flow rapidly deteriorates as the thermal boundary layer develops.

抄録全体を表示

In manufacturing technology, it is a dominant tendency in recent years that machine tools for turning, milling and so on, employ electric operated actuators such as a servo-motor equipped with a ball screw. The problems with these electric driving machine tools are, they are excessively large-sized with complex machinery and they are expensive, as seen in their application to, for example, NC-machine. In order to solve these problems, we developed a precision driving system actuated by a hydraulic cylinder in the previous report of this study. This present report deals with the ability test of turning, drilling and milling by applying the previously developed driving system to a micro-machine-tool. The cutting results were compared with the ones obtained by conventional NC-machines. It was confirmed that the developed machine has superior ability over the conventional ones.

抄録全体を表示

A power-assisted chair is designed to help user motion with a pneumatic cylinder. Force of the cylinder is controlled to be proportional to the seat angle. The control leads to virtual spring characteristics. In this paper, the virtual spring characteristics are modified to make the spring constant variable depending on the seat angle. Another function of the chair, which is added in this paper, is a function of locking the seat at the top position. Combining these control techniques, a control technique called total mode control is proposed.

抄録全体を表示

An optimized finite element model is applied to simulation of turbulent transient flow in pipes. The turbulent friction is a nonlinear function of flow rate. It can be evaluated without linearization when using the optimized finite element model. The model is written as a state space equation, whose coefficient matrices are obtained on the assumption of non-loss pipes. A turbulent friction term is introduced into the model as an augmented block. The turbulent friction block is a combination of a block of the square of the flow rate and a block of a frictional coefficient. The model can be applied to simulation-tool software such as simulink. Experiments are carried out using an open-end pipe. Simulated results are compared with experimental results to reveal the accuracy.

抄録全体を表示