The rotational speed sensor is a sensor that converts the rotational speed of a rotating object into an electrical output. The commonly used types are: photoelectric, eddy current, magnetoresistive, Hall, capacitive, proximity switch, etc. The magnetoresistive, eddy current and Hall speed sensors are all based on the basic principle of electromagnetic induction to realize the speed measurement, and they are all magnetoelectric speed sensors. Magnetoelectric speed sensors are widely used in industrial production, such as electric power, automobile, aviation, textile and petrochemical fields, to measure and monitor the speed parameters of mechanical equipment, and to achieve automatic management and control. Therefore, establishing a scientific and reliable calibration method of magnetoelectric speed sensor has become an urgent requirement of metrology work. This paper expounds the measurement principle of the magnetoelectric speed sensor.
Active or passive magnetoelectric speed sensor, its measurement methods are all non-contact. The magnetoresistive and eddy current rotational speed sensors sense and measure objects with convex or concave magnetic materials and magnetically permeable materials. The working principle is shown in Figure 1(a). based on the eddy current effect. When the tachometer wheel rotates, the gap between the gear and the sensor changes periodically, and the magnetic flux also changes at the same period, so that the sensor senses a pulse signal that changes periodically. The Hall-type speed sensor needs to install a magnet on the rotating object to change the magnetic field around the sensor, so that the sensor can accurately capture the motion state of the object to be measured. Its working principle is shown in Figure 1(b). When the magnetic field line passes through the sensing element on the sensor, a Hall potential is generated and converted into an alternating electrical signal, and the built-in circuit of the sensor adjusts and amplifies the signal and outputs a pulse signal.
With the rotation of the measured object, the rotational speed sensor outputs a pulse signal (approximately sine wave or rectangular wave) corresponding to the rotational speed, and the measured rotational speed value is displayed by the counter.