Daido Tokushuko Kabushiki Kaisha

Nissan Motor Company Limited

Sumitomo Electric Industries, Limited

Daido Steel Co., Ltd.

Takanobu Saito

Shinichiro Yahagi

Hiroyuki Aoki

Satoshi Takemoto

Atsushi Yoshida

Kenji Miyazaki

Munekatsu Shimada

Katsuhiro Kojima

Masashi Mizuno

Masaaki Katsumata

Shinichi Kitamura

Toshiaki Yashiro

Yoji Ozawa

Haruo Koyama

There is disclosed a powder magnetic core in which a permeability does not easily drop even when an applied magnetic field intensifies, comprising: a bulk body containing a main component of a powder of an Fe-base alloy having a soft magnetic property, and the balance substantially including a heat-treated insulation binder and a void,

Powder magnetic core

A powder magnetic core mainly comprises a soft magnetic powder which contains: 0.5 to 15% by mass of Si; 10% by mass or less of Al; and the balance of Fe and unavoidable impurities. The powder has an apparent density/true density falling within in a range of 0.4 to 0.55, and a volume percentage of the soft magnetic powder is 80% by volume or more. An initial permeability of the core at 100 kHz is 125 or more.

A magnetic mixture comprising at least two kinds of powders which are uniformly mixed with each other. Each powder exhibits a significant magnetic property when its constituent elements have a predetermined composition ratio. Magnetic properties of each powder are retained in the magnetic mixture which exhibits, as a whole, a soft magnetic property. The magnetic mixture is useful as a raw material for a powder magnetic core.

Magnetic mixture

A powder magnetic core is made from powder containing Fe-based soft magnetic powder as a major component. Provided that an initial permeability of the core is &mgr; and that a permeability of the core observed when a magnetic field of 24 kA/m is applied to the core is &mgr;, &mgr; and &mgr; fulfill the relationship &mgr;/&mgr; &gE;0.5. Specifically, the powder magnetic core is made from 60 to 75 volume % of soft magnetic powder having an aspect ratio (L /L ) of 1 to 1.5 and the balance containing an insulating binder as a major component, and the content of the insulating binder is 5 to 20 parts by weight with respect to 100 parts by weight of the soft magnetic powder. The powder magnetic core shows a small reduction in the permeability even when the strength of a magnetic field applied thereto is increased.

An INVAR.RTM. or iron nickel alloy or iron nickel cobalt alloy wire has an area ratio of carbide existing at the grain boundaries of the wire in the finished wire of at most 4%, or an average grain size in the transverse direction within a range of 1 to 5 .mu.m. Such a wire has a superior twisting property.

Iron alloy wire and manufacturing method

A torque sensor provides a specific property for a shaft member so as to improve sensitivity and so as to minimize hysteresis in measurement of the torque exerted thereon. The shaft member is provided specific composition achieving the desired level of sensitivity without increasing the hysteresis. In the alternative, the shaft member is processed in order to provide the desired property.

Torque sensor

A torque detecting device has a measuring shaft, an excitation device and a detector for detecting a magnetostriction passing through said measuring shaft. The device is able to measure the torque with accuracy even if a temperature gradient is produced in the axial direction of the measuring shaft by making the measuring shaft from a material having specified electromagnetic characteristics at least in a part in which said magnetostrictive force is detected.

Torque detecting device

A magnetostriction type torque sensor employs a plurality of detector coils arranged in axial arrangement along an objective rotary body. The detector coils are so designed and arranged as to compensate influence of temperature, particularly the error caused due to axial temperature gradient caused in the objective rotary body.

Magnetostriction type torque sensor with temperature dependent error

A torque detecting device has a measuring shaft and a magnetic circuit incorporating the measuring shaft into a magnetic path which includes a device for detecting a magnet-ostrictive force passing through said measuring shaft. The device is able to increase the output sensitivity, decrease the rotative fluctuation of output and decrease the hysteresis by making the measuring shaft forming the magnetic path from an iron base alloy having a specific composition.

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Okazaki, Japan

Takanobu Saito