Time filter

Source Type

Usui T.,Kyoto University | Matsuhisa H.,Kyoto University | Utsuno H.,Kyoto University | Yamada K.,Kyoto University | Yasuda M.,Tokkyokiki Corporation
17th International Congress on Sound and Vibration 2010, ICSV 2010 | Year: 2010

Reducing damages against earthquakes has been an important issue for decades. This study proposes a three-dimensional seismic isolator, which also can reduce the vibrations caused by not only earthquakes but also force acting on the object on the isolator. Then this system can be called the vibration controller/isolator. The MR (magneto rheological fluid) damper was used to change the damping coefficient according to the control algorithm. When the base shakes and isolation is needed the damping coefficient must be small and when the force acts and damping force is needed the damping coefficient must be large. Then the damping coefficient of MR damper was controlled according to displacements and velocities of the base and the object. The isolator must keep horizontal otherwise the object on the isolator easily falls down. Therefore, the system had a tilt prevention mechanism by means of parallelogram linkages. Two units of linkages, each of which consists of two parallelograms, were used for the three-dimensional motion. The performance of the proposed isolator was investigated by both simulation and experiment. Since the MR damper had not only rheological damping force but also friction force, the friction force was considered in the theoretical analysis. The results showed that the vibration caused by force was reduced very well and the vibration caused by the motion of base was also reduced well. Since the structure is very simple and effective, this system can be applied not only to seismic isolator but also to IC tip production systems and to precision measuring devices. Source

Asami T.,University of Hyogo | Yokota Y.,University of Hyogo | Ise T.,University of Hyogo | Honda I.,University of Hyogo | Sakamoto H.,Tokkyokiki Corporation
Journal of Vibration and Acoustics, Transactions of the ASME | Year: 2013

This paper proposes a simple expression for calculating the restoring and damping forces of an air spring equipped with a small pipe. Air springs are commonly used in railway vehicles, automobiles, and various vibration isolators. The air spring discussed in this study consists of two tanks connected by a long pipe. Using a pipe instead of an orifice enables flexibility in the arrangement of the two tanks. In addition, this makes it possible to manufacture a thin air spring. A vertical translational oscillating system, which consists of a single mass supported by this type of air spring, looks like a single-degree-offreedom (SDOF) system. However, it may have two resonance points. In this paper, we propose a vibratory model of a system supported by the air spring. With the proposed model it is possible to correctly reproduce the two resonance points of a system consisting of a single mass supported by this type of air spring. In our analysis, assuming that the vibration amplitude is small and the flow through the pipe is laminar, we derive the spring constant and damping coefficient of an air spring subjected to a simple harmonic motion. Then, we calculate the frequency response curves for the system and compare the calculated results with the experimental values. According to the experiment, there is a remarkable amplitude dependency in this type of air spring, so the frequency response curves for the system change with the magnitude of the input amplitude. It becomes clear that the calculation results are in agreement with the limit case when the input amplitude approaches zero. We use a commercially available air spring in this experiment. Our study is useful in the design of thin air spring vibration isolators for isolating small vibrations. Copyright © 2013 by ASME. Source

Asami T.,University of Hyogo | Yokota Y.,University of Hyogo | Ise T.,University of Hyogo | Honda I.,University of Hyogo | Sakamoto H.,Tokkyokiki Corporation
Journal of Vibration and Acoustics, Transactions of the ASME | Year: 2013

We herein propose a simple but accurate method for calculating the dynamic properties of an air spring that uses an orifice to produce a damping force. Air springs are commonly used in rail, automotive, and vibration isolation applications. However, because this type of air spring has nonlinear flow characteristics, accurate approaches have not yet been proposed. The restoring and damping forces in an air spring with an orifice damper vary with the amplitude of the body. This amplitude dependency has not been considered in previous studies. We herein propose a simple model for calculating the air spring constant and damping coefficient. However, this requires iterative calculation due to the nonlinearity of the air spring. The theoretical and experimental results are found to agree well with each other. The theoretical equations provide an effective tool for air spring design. © 2013 American Society of Mechanical Engineers. Source

Tokkyokiki Corporation | Date: 2011-07-29

In a conventional hard material insulator, reproduced sound can be tuned with use of characteristics of the material; however, various types of acoustic materials have specific high frequency characteristics, and thus their acoustic effects lack versatility, require compatible audio devices, and change with environment, musical genre, etc. To address this, a wind-bell member (resonant member) is arranged in parallel with a main propagation path of vibration transferred from an audio device to an insulator. Accordingly, a vibration system of a wind-bell having a tone determined by many factors such as a fundamental tone, harmonic tones, lingering sound, and fluctuation assists (enhances) high frequency vibration propagated from the audio device. As a result, due to the above assist action that is different in principle from a conventional type, acoustic characteristics such as a sense of localization, resolution, and a sense of transparency and scale a sound image can be dramatically improved.

Yoshida K.,Nagoya University | Yoshida K.,Japan Fine Ceramics Center | Tominaga T.,OS Engineering Corporation | Hanatani T.,Tokkyokiki Corporation | And 6 more authors.
Journal of Electron Microscopy | Year: 2013

We present further modifications to aberration-corrected environmental transmission electron microscopy (AC-ETEM) for the dynamic HRTEM observation of single atoms. Additional pumping levels that include three additional turbomolecular pumps (TMPs) enable a base pressure of 3.5 × 10 -5 Pa in the sample chamber. The effect of these additional TMPs on image resolution was measured in reciprocal space using information limit (Young's fringes) on a standard cross grating sample and also with platinum (Pt) single atoms on an amorphous carbon film (Pt/a-carbon). The Pt/a-carbon was used for measuring the effect of gas pressure on single-atom imaging in addition to the evaluation of vibrations of TMPs, samples, magnetic lenses and a microscope column of the AC-ETEM. TMPs did not affect the ETEM imaging performance when an anti-vibration table was used, and 0.10-nm resolution was achieved. Dynamic ETEM observation of Pt single atoms was achieved in 4.0 × 10-2 Pa of air, using a modified AC-ETEM system and a high-speed CCD camera with a time resolution of 0.05 s. © 2013 The Author. Source

Discover hidden collaborations