Eddy current sensor and eddy current measurement method

An eddy current sensor that includes:

• a probe having an exciting portion for applying a predetermined alternating-current excitation signal to a measurement object component and a detecting portion for detecting a detection signal generated in the measurement object component owing to the applied alternating-current excitation signal;
• and a computing unit for calculating the detection signal as a measured eddy current value, and that is formed in a prismatic shape of which an axis is oriented in a first axis direction, characterized in that
• the exciting portion includes a first excitation coil that is wound so that a center axis direction of the first excitation coil is oriented in the first axis direction, a second excitation coil that is wound to intersect with the first excitation coil so that a center axis direction of the second excitation coil is oriented in a second axis direction perpendicular to the first axis direction, and a third excitation coil and a fourth excitation coil that are wound to intersect with the first excitation coil so that center axes directions of the third excitation coil and fourth excitation coil are oriented in directions perpendicular to the first axis direction and inclined equally with respect to the second axis direction,
• the detecting portion includes a first detection coil that is arranged at one of two intersecting portions of the first excitation coil and the second excitation coil, a second detection coil that is arranged at one of two intersecting portions of the first excitation coil and the third excitation coil, adjacent to the first detection coil, and a third detection coil that is arranged at one of two intersecting portions of the first excitation coil and the fourth excitation coil, adjacent to the first detection coil, and
• alternating-current voltage is applied to each of the first excitation coil, the second excitation coil, the third excitation coil and the fourth excitation coil as the alternating-current excitation signal, in a state where the probe is arranged in proximity to the measurement object component in position such that the first detection coil faces a measured portion of the measurement object component to generate magnetic fields in the measurement object component to thereby generate eddy currents by the magnetic fields, induced voltages generated by the eddy currents are detected by the first detection coil, the second detection coil and the third detection coil as detection signals, the computing unit calculates the detection signals as measured eddy current values to thereby measure hardness penetrations of the portions of the measurement object component, respectively facing the first, second and third detection coils, on the basis of the measured eddy current values.

An eddy current sensor that includes:

• a probe having an exciting portion for applying a predetermined alternating-current excitation signal to a hollow measurement object component and a detecting portion for detecting a detection signal generated in the hollow measurement object component owing to the applied alternating-current excitation signal;
• and a computing unit for calculating the detection signal as a measured eddy current value, characterized in that
• the exciting portion includes a first excitation coil that is arranged so that a center axis direction of the first excitation coil is oriented in a first axis direction and a second excitation coil that is arranged to intersect with the first excitation coil so that a center axis direction of the second excitation coil is oriented in a second axis direction perpendicular to the first axis direction,
• the detecting portion includes two detection coils that are arranged at both intersecting portions of the first excitation coil and the second excitation coil, and
• alternating-current voltage is applied to each of the first excitation coil and the second excitation coil as the alternating-current excitation signal in a state where the probe is arranged in proximity to the hollow measurement object component in position such that the probe is inserted in the hollow measurement object component and the detection coils each face an inner peripheral surface of the hollow measurement object component to generate a first magnetic field in the first axis direction and a second magnetic field in the second axis direction at portions of the hollow measurement object component, facing the respective detection coils, to thereby generate eddy currents in the measurement object component by the magnetic fields, induced voltages generated by the eddy currents are detected by the detection coils as detection signals, the computing unit calculates the detection signals as measured eddy current values to measure hardness penetrations of the portions of the measurement object component, respectively facing the detection coils, on the basis of the measured eddy current values.