STRAIN MEASURING INSTRUMENT

Japanese Patent JPH03194430

A

PURPOSE:To obtain the strain measuring instrument which is free from a detection error due to temperature variation and simplified in manufacture process by providing a magnetic shielding layer nearby at the periphery of a driven member and fixing it inside a detection coil. CONSTITUTION:When a high frequency current is supplied to the detection coil 3, high frequency magnetic flux is produced. The magnetic flux attenuates in density on the surface of a conductor according to exp[-(omegasigmamu/2)<1/2>]. Here, omega is each frequency of the magnetic flux, sigma is the conductivity of the conductor, and mu is the magnetic permeability of the conductor. The penetration depth delta of the magnetic flux is there fore represented as delta=(2/omegasigmamu/2)<1/2> and the magnetic shielding layer becomes small in delta since sigma is small. For the purpose, the thickness of the shielding layer 2 is made larger than delta, and then the magnetic flux does not enter the part of the driven member 1 covered with the shielding layer 2 and enters only the slit 4. When an external force such as torque is applied to the member 1, a strain is caused in the member 1 to vary magnetic permeability and magnetic impedance. Therefore, the strain quan tity can be measured from the extents of variation of two coils 3. No thermal stress is generated since the member 1 and layer 2 are not joined, and the fixation of the layer 2 simplifies the manufacture process.

JP5002981	Torque sensor
JP3950567	TORQUE MEASURING APPARATUS
JPH05164632	MANUFACTURE OF MAGNETOSTRICTIVE TORQUE SENSOR

HASEGAWA MASAHIKO
HONDA HIROHIKO

JP33392489A

August 26, 1991

December 22, 1989

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MITSUBISHI ELECTRIC CORP

G01L3/10; G01B7/00; G01B7/24; (IPC1-7): G01B7/24; G01L3/10

Masuo Oiwa (2 outside)

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