Hybrid Products Division

Japan

Hybrid Products Division

Japan
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Kitada H.,Hybrid Products Division
SEI Technical Review | Year: 2017

Air springs are part of a soft damping suspension system that provides both softness and damping characteristics by utilizing the compressibility and flow resistance of air. They were first used on railways about 60 years ago. The subsequent and continuous advancement of air spring technology is a result of the incorporation of air springs into Shinkansen trains and the acceleration of R&D activities in overcoming various challenges associated with increasing train speeds. To reduce the environmental impact of high-speed trains, the weight of each car was reduced dramatically. In particular, adoption of bolster-less bogies reduced car weight. Together with such technological innovations, the functions of air springs also changed remarkably. To make the Shinkansen competitive with aircraft by increasing both speed and ride quality, various new functional units were developed. Such units include the horizontally nonlinear air suspension system and the car-body tilting system with built-in air springs that enables trains to travel at higher speeds on curved tracks. A project aimed at further increasing train speed has been launched for several train lines. We will continue our R&D efforts to develop air springs that will enable trains to run safely at speeds exceeding 320 km/h while providing a truly comfortable ride.


Geshi K.,Hybrid Products Division | Teraoka K.,Hybrid Products Division | Tsuji Y.,Hybrid Products Division | Fujii A.,Hybrid Products Division | And 5 more authors.
SEI Technical Review | Year: 2012

This paper proposes use of polycrystalline spinel for the temperature compensation of radio frequency (RF) surface acoustic wave (SAW) devices. Spinel can be bonded with LiTaO3 (LT) and LiNbO3 (LN) wafers by using adhesive and direct bonding techniques. A series of RF SAW resonators were fabricated on the LT(LN)/spinel structure, and their performance, including the temperature coefficient of frequency (TCF), was measured. For comparison, SAW resonators employing Si and sapphire in place of spinel were also fabricated. The result indicated that the polycrystalline spinel offers TCF improvement better than other materials.

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