Hitachi, Ltd.

Hitachi Video Engineering, Incorporated

Hitoshi Okabe

Toru Tanimizu

Katsuhiro Komuro

Yoshimi Hakamata

Masato Kobayashi

Noboru Baba

Shigeru Kikuchi

Yoshitaka Kojima

Ikuo Nishida

Ryo Hiraga

Juichi Morikawa

Makoto Ibe

Hideyuki Kawase

Akira Wada

Masanori Kochi

Toshio Osada

Hitoshi Takizawa

Katsumi Kuroda

Eiichi Hanawa

Kathumi Kuroda

Tosio Uno

The invention aims at providing a vacuum circuit-breaker, a vacuum valve used therein and electrodes for the vacuum valve, which can reduce the manufacturing cost while being of high performance and compact in size. The invention resides in a vacuum circuit-breaker, a vacuum valve and electrodes for the vacuum valve, which are characterized in that fixed and movable electrodes each comprise arc electrodes, whose entire surfaces, mutually facing each other, are made of an alloy containing a refractory metal and a highly conductive metal, and electrode rods of a highly conductive metal supporting the respective arc electrodes, and that each arc electrode and the mating electrode rod are integrally formed by means of solid-phase diffusion bonding.

Vacuum circuit-breaker, vacuum bulb for use therein, and electrodes thereof

Disclosed is a vacuum circuit breaker including a small-sized electrode structure capable of reducing deformation with age thereby enhancing the reliability and a vacuum bulb and a vacuum bulb electrode used for the breaker. In the vacuum circuit breaker, each of a fixed electrode and a movable side electrode includes an arc electrode made from particles of a refractory metal material, a high conductive metal material and a low melting point metal; an electrode supporting portion, made from the high conductive metal material, for supporting the arc electrode; a back conductor having a diameter smaller than the electrode supporting portion; and an external side connecting portion having a diameter larger than that of the back conductor. The arc electrode is integrated with the electrode supporting portion, back conductor, and external side connecting portion by the high conductive metal material, preferably, by melting of the highly conductive metal material.

Vacuum circuit breaker, and vacuum bulb and vacuum bulb electrode used therefor

An electrode for a vacuum circuit breaker provided with a connecting portion made of a material having the same resistivity as the arc running face portions across the corresponding arc guiding channel at the outer circumferential end thereof, wherein when the outer diameter of the connecting portion is D.sub.1 and the inner diameter of the connecting portion is D.sub.2, the width of the connecting portion is designed so that the ratio D.sub.2 /D.sub.1 is in a range of more than 0.9 and less than 1.0. An arc generated between the electrodes is magnetically driven over the arc running face portions via the connecting portion so that the current interrupting capacity of the electrode is increased and the size and weight of the electrode are reduced.

Electrode for vacuum circuit breaker

A rotary magnetic head cylinder device for use in a helical-scanning system video tape recorder has a projection provided on a tape running race of a stationary lower cylinder near a location at which a magnetic tape leaves from the lower cylinder. The projection is preferably integral with the tape running race and has a small area which is defined by a shoulder circumferentially extending identically with a tape guide shoulder contouring the lower edge of the tape running race and which spreads perpendicularly to the tape running race, and an upper surface coplanar with the top face of the lower cylinder, and a height defined by a protruded length radially outwardly toward the outer circumferential surface of the lower cylinder. The projection serves to reduce vibrations of the magnetic tape generated when the video head carried by the rotary upper cylinder leaves from the magnetic tape.

Rotary magnetic head cylinder device for suppressing vibrations ofa

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Hitachi, Japan

Hitoshi Okabe