TRANSACTIONS OF THE JAPAN FLUID POWER SYSTEM SOCIETY
Online ISSN : 1349-7022
Print ISSN : 1880-3121
ISSN-L : 1349-7022
Volume 36, Issue 6
Displaying 1-4 of 4 articles from this issue
Paper
  • Toshiro NORITSUGU, Lei GAO
    2005 Volume 36 Issue 6 Pages 143-151
    Published: 2005
    Released on J-STAGE: October 26, 2006
    JOURNAL FREE ACCESS
    This Study focuses on the development of a safe power assist device that supports hip motion in those people who do not have the full range of such motion using an artificial curved pneumatic rubber muscle and wearable garment. Soft texture and lightness of weight allow the power-assist device to be worn directly on the body similar to a coat. The device is soft and fits easily on the body. The artificial rubber muscle is fixed on the outfit. The device is safe and greatly mitigates the burden to the body. A soft touch-sensor activates the device automatically. The soft touch-sensor consists of fifty silicone rubbers cylinders that are fixed on two acrylic boards. The sensor sets between the garment and the back of the body. A Tilt-angle sensor fixed on the upper part of a link connects with rod of outfit. The angle of torso tilt determines the pressure desired for the artificial rubber muscle. The soft touch-sensor and tilt-angle sensor provide communication between the entire system and the human body. Analyses of the experimental data prove the support efficiency of the proposed power assist device.
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  • Tatsuo WAKAHARA, Tetsuya IZUMI, Toshiji IIDA, Hirohisa TANAKA
    2005 Volume 36 Issue 6 Pages 152-157
    Published: 2005
    Released on J-STAGE: October 26, 2006
    JOURNAL FREE ACCESS
    A new-generation belt type Continuously Variable Transmission ranging up to 3.5 liter class engine is on the market. This CVT contributes to improvement in both efficiency and performance. This article describes a ‘control method’ newly developed for this CVT pulley ratio control. In the former control system, pulley ratio was controlled only by step-motor. Extra margin of line pressure was indispensable compared to primary pressure to accomplish target-ratio. If line pressure was not sufficient for primary pressure, pulley ratio couldn't be controlled accurately, and would be lower. On the other hand, in this new control, characteristics of hydro-mechanical shift system are utilized positively, and pulley ratio can be controlled by not only step-motor but also linear solenoid for line pressure. At this time, the most suitable line pressure is searched for by confirming the relation between command of step-motor and pulley ratio. In the result, line pressure can also be reduced a little less than primary pressure without causing unpleasant pulley ratio hunting.
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  • Ato KITAGAWA, Haifan WU, Hideyuki TSUKAGOSHI, Sung-Hwan PARK
    2005 Volume 36 Issue 6 Pages 158-164
    Published: 2005
    Released on J-STAGE: October 26, 2006
    JOURNAL FREE ACCESS
    This study is concerned with the development of a novel portable pneumatic power source applicable to mobile applications such as wearable actuator and rescue robot etc. The dry-ice, which is the solid phase of the carbon dioxide, is chosen as the source of the power for the developed power source because it is nonpoisonous, easy to obtain, low in price and it expands 750 times in volume after being vaporized into the gas. When dry-ice is stored in the confined pressure container, the pressure and temperature rise by heat transfer and it begins to liquefy after the pressure and temperature reach the triple point (0.52 [MPa (abs)] , -56°C). In this process the pressure remains constant until all the dry-ice melts into the liquid. When the state remains at triple point, the pressure does not decrease even though the gas is released from the pressure container. Accordingly, this means that the state can be used as a stable pneumatic power source. By using this physical property of carbon dioxide at the triple point, and by controlling the heat transfer from the surroundings into the pressure container, a noiseless, large capacity, light and portable pneumatic power source is developed. In this paper, the structure and the flow characteristic of the pneumatic power source is described in detail.
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  • Koki TOMIOKA, Kazuhiro TANAKA, Hiroaki YOTSUMOTO, Katsuya NAGAYAMA
    2005 Volume 36 Issue 6 Pages 165-170
    Published: 2005
    Released on J-STAGE: October 26, 2006
    JOURNAL FREE ACCESS
    Recently an oil-hydraulic system has been made which is compact and high-pressured. That causes a steep rise of the system temperature because of the small heat volume and large heat generation. When the system has risen so much, characteristics of the working oil deteriorate and the system is finally dangerous.
    It is very important to study a simple and precise way to predict the temperature rise of the system. As the first step, heat generation and heat transfer in an oil-pipe were modeled and calculated in the present paper. The oil-flow dynamics with the heat generation mechanism was modeled one-dimensionally using ordinary differential equations by the Bondgraph method, which is very convenient for modeling and simulation of heat generation because the method is based on the power transmission. On the other hand, the heat transfer in the housing was analyzed three-dimensionally using the partial differential equation of heat conduction. The prediction of the temperature distributions was calculated effectively by coupling these two kinds of equation systems. The simulation result was compared with the result of the commercial code results and they agreed very well.
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