Research And Application Of Displacement Sensor Based On Magnetic Control Method

The content of this thesis is a sub-project of the "Development of Coal Face Unattended Electro-hydraulic Control System"(No. OS2013ZR0493) of International Science and Technology Cooperation Projects, and an important component of the Shanxi Key Thematic Science and Technology Projects "Research of Technology and Equipment in Domestic Fully Mechanized Working Face"(No.20111101024). This thesis is proposed against the backdrop that there is still dependence on imported displacement sensors in the electro-hydraulic control system of hydraulic supports.The unmanned automatic control system for the fully-mechanized mining face is the core of automation of the coal mining industry, to which the electro-hydraulic control system of hydraulic supports is the key. It determines the stable and continuous performance of the coal mining machine and the scarper conveyor whether the hydraulic supports is in place. The displacement sensor in the pushing-moving oil cylinder senses real-time displacement of the pushing-moving oil cylinder, converts the signal into voltage signal, and sends it to the electronic-hydraulic controller in the hydraulic supports, which then performs the accurate pushing-moving action of the oil cylinder. Therefore, the displacement sensor is a key of the whole system. However, research and technological advances on the displacement sensor is still insufficient in China compared to Western developed countries in terms of accuracy and resolution. Therefore, the development of independent intellectual property rights and the passage of the stent displacement sensor which were used in hydraulic cylinder is of greatly practical significance.This thesis aims to develop a displacement sensor used in the electronic-hydraulic control system. The structure of the sensor magnet was optimized through the magnetic field simulation. This sensor applies non-contact measurement method which guarantees high accuracy, stability, simple structure, easy-equipment, and anti-pollution features. The main contents are as follows:In this paper, the development situation and the development trends of the displacement sensor is analyzed seriously based on a large number of related domestic and international literatures. By comparing the characteristics of various displacement sensors, as well as considering the structure and working methods of the hydraulic support, the design scheme of the displacement sensor based on magnetic control is made.The distribution of the magnetic field is analyzed based on the equivalent magnetic charge theory and the curves of the results by Matlab software is presented in this paper. In addition, the paper uses Ansoft Maxwell simulation software to verify the correctness of the calculation result.The reed switches, the magnetic material the stainless steel materials and the cable the displacement sensor needs is ensured for the different characteristics of materials of the displacement sensor, and a displacement sensor based on magnetic control is produced finally. It is proved that the displacement sensor is Effective and Feasible by the experiment.A detection device for the displacement sensor is designed in this paper to be used for testing the detection performance of the magnetic control displacement transducer. This device includes a linear sliding table, a drive, a control circuit and the display. The control circuit sending a pulse signal to the driver, the driver driving the stepper motor on the linear slide table to act, the linear slide table slide driven the movement of the magnetic ring, the display showing the output signal of the sensor in real time.Many tests for the displacement sensor’s performance such as linearity, error, aging stability, moisture stability, temperature stability are taken here. It has been shown by the experiment in laboratory and measurement in field that the displacement sensor has a high stability, Accuracy and linearity, which shows that the displacement sensor can be used to measure the moving position of the hydraulic support accurately and stably. Owing to the simple structure, easy installation and the good antipollution performance, this displacement sensor is suitable to be used in the pushing-moving oil cylinder of the hydraulic support.