Matsushita Electric Industrial Co., Ltd.

Shinya Tokuono

Hiroyuki Hase

Masayuki Wakamiya

Ichiro Yamashita

A torque sensor comprising strips of an amorphous magnetic alloy fixed to the surface of a rotary shaft so as to utilize a inverse magnetostrictive effect of the amorphous magnetic alloy is operated in a state in which a predetermined amount of internal compressive strain is previously produced in the strips, so that the torque sensor can operate without any temperature-dependent change in its sensitivity and without occurrence of a hysteresis of its output.

Torque sensor

The long-term measurement stability of a magnetostrictive effect strain or stress sensor that uses an amorphous magnetic alloy excited by a magnetic field is improved by generating a magnetic field from an electric current formed from a superposed alternating current waveform and a recurring rectangular current waveform that has a larger amplitude at its start-up and which converges to a smaller amplitude after a predetermined time period or an electric current formed from a superposed direct current component and an alternating current component having constant amplitude and a frequency that varies in a recurring manner between a high frequency and a lower frequency.

Method of operating an amorphous-magnetic-alloy sensor

A torque sensor includes a cylindrical body disposed concentrically around a shaft and having its opposite ends secured to the surface of the shaft through elastic bodies, a layer of soft magnetic alloy having a magnetostriction property and secured to the surface of the cylindrical body, and a coil disposed concentrically around the layer with an air gap between it and the layer. The torque sensor is constructed such that a strain produced on the surface of the cylindrical body by a torque is converted into a change of a relative permeability of the soft magnetic alloy due to a reverse magnetostriction effect which is detected as a change of inductance of the coil. When the shaft thermally expands or deflects, the elastic bodies act to permit only a torque to be transmitted to the cylindrical body, so that a uniform output is provided without the influence of a thermal strain and deflection of the shaft.

Magnetically operated non-contact magnetic torque sensor for shafts

A torque sensor which includes a pair of multiple thread portions integrally formed in the surface of a rotating shaft in such a manner that one of the multiple thread portions forms a positive angle with the thrust direction of the rotating shaft and the other forms a negative angle with the thrust direction. The threads of the multiple thread portions are at least made of soft magnetic alloy having magnetostrictive properties. A pair of coils are arranged concentrically on the outer side of the multiple thread portions at a given distance therefrom. The strain produced in the surface of the rotating shaft is detected as inductance changes of the coils when the permeability of the soft magnetic alloy changes. The direction and magnitude of the torque are detected because of the difference between the inductances of the coils.

A fluid pressure sensor includes a body made of a soft magnetic material with a groove formed therein, and a coil is installed in the body in the groove. One magnetostrictive disc is placed on the body over the groove, and two non-magnetic discs are placed over the magnetostrictive disc. A casing is provided for accommodating the body carrying the coil, the magnetostrictive disc, and the non-magnetic discs, and it is closed by a lid member which has a surface for receiving a fluid pressure. A plurality of through holes are formed in the lid member within the fluid pressure receiving surface such that the through holes extend to the non-magnetic disc at position over the groove, whereby the magnetostrictive plate is partially distorted by the fluid pressure.

Growing community of inventors

Ashiya, Japan

Shinya Tokuono