Principle of inductive sensors classification of i

2022-07-22
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Based on the principle of coil self inductance change, inductive sensors have been widely used in various fields of industrial control industry. Its advantages are: no mechanical moving parts, long service life, high sensitivity, high precision, high output frequency, easy on-site installation and maintenance, etc

inductive sensor mainly uses the principle of electromagnetic induction to convert the measured physical quantities such as displacement, pressure, flow and vibration into the changes of self inductance coefficient and mutual inductance coefficient of the coil, and then convert them into the changes of voltage or current output by the circuit, so as to realize the conversion from non electric quantity to electric quantity. The following editor will introduce the principle and classification of inductive sensors

principle of inductive sensor

the basic principle of inductive sensor is the principle of electromagnetic induction, that is, the measured non electric quantity (such as pressure, displacement, etc.) is converted into the change output of inductance by electromagnetic induction, and then the change of inductance is converted into the change of voltage or current through the measurement conversion circuit to realize the measurement of non electric quantity. Such inductors mainly include variable air gap inductive sensor, differential solenoid inductive sensor, differential transformer inductive sensor and eddy current inductive sensor

classification of inductive sensors

commonly used inductive sensors include variable gap type, variable area type and screw tube iron insert type. In practical use, these three kinds of sensors are mostly made into differential type, so as to improve linearity and reduce the additional deviation formed by electromagnetic suction. The air gap of the variable gap inductance sensor changes with the measured change, thus changing the magnetoresistance. Its sensitivity and nonlinearity decrease with the increase of the air gap, so it is often necessary to consider the integration of the two. The absolute shrouded area between the iron core and armature of the variable area inductance sensor changes with the measured change, thus changing the reluctance. Its sensitivity is constant and its linearity is also very good. The solenoid iron inserted inductive sensor is formed by the solenoid coil and the cylindrical armature connected with the measured object. The principle of its task is based on the change of magnetoresistance on the leakage path of the magnetic field line of the coil. The armature changes the inductance of the coil when it moves with the measured object. The sensor has large range, low sensitivity, simple structure and is easy to manufacture. Since the above three kinds of sensors are mostly made of differential type, inductive sensors are fundamentally divided into variable reluctance sensors &mdash& mdash; Self induction type; Differential transformer sensor &mdash& mdash; Mutual inductance type; Eddy current sensor &mdash& mdash; Three kinds of eddy current type

differential transformer sensor is a sensor that converts the measured non electric quality change into coil mutual inductance change. High measurement accuracy, high sensitivity, simple structure and reliable function

eddy current sensor applies eddy current effect &mdash& mdash; When a bulk metal conductor is placed in a changed magnetic field or cuts magnetic lines of force in the magnetic field, a vortex like sensing current will occur in the conductor

requirements for use of inductive sensors

1. Attenuation of detection distance. The slip and warpage are made of iron, which is suitable for inductive sensor detection; The size of the measured part of the slip warping is slightly smaller than the size of the standard test object (the size of the standard test object is 3 times the rated detection distance, in this application, the standard size should be 120*120mm), so there will be a certain attenuation

2. On site anti-interference ability. This is a problem that cannot be ignored. Ordinary inductive sensors are easy to be interfered by motors or frequency converters. Many technicians only choose sensors with strong anti electromagnetic interference for applications near here. However, in the automobile manufacturing workshop, the workshop is large, and the on-site technicians are used to using walkie talkies for communication, especially when walking and talking with walkie talkies, they will inadvertently approach the sensor, resulting in short-term failure

3. Installation. With the popularity of inductive sensors, sensors not only improve their electrical performance, but also their mechanical design is becoming more and more humanized. To maximize the humanization of installation. It reduces the preparation of a variety of similar products and reduces the time of installation and maintenance

4. Guarantee of stable operation. In the use of the car factory, it is necessary to put an end to any erosion of oil and dust. In addition, when sliding and warping through the track, the vibration exists for a long time, and the excellent vibration resistance also plays a very important role

inductive sensor features

1. The structure is simple, and the sensor has no active electrical contact, so it works reliably and has a long service life

2. It has high sensitivity and resolution. It can measure the displacement change of 0.01 micron, and its output signal is strong. The voltage sensitivity is generally hundreds of millivolts per millimeter

3. The linearity and repeatability are relatively good. Within a certain displacement range, the nonlinear error of the sensor can reach 0.05% - 0.1%

editor's summary: This is the introduction of the principle and classification of inductive sensors. I hope it will be helpful to you. If you want to know more, you can pay attention to information

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