Design Of Screening System For Temperature Characteristics Of Diaphragm Of Temperature Protector

The temperature controller is a device used to sense and control the temperature.It is widely used in the overheating and overcurrent protection of electrical appliances,compressors,lighting fixtures and household appliances.Its main working principle is that the bimetallic diaphragm will jump suddenly with the change of temperature.When the temperature rises to a certain temperature,the bimetallic diaphragm will lose its stability and deform,causing a larger end of the diaphragm.Deformation,the contact is disconnected;When the temperature drops to a certain temperature,the diaphragm will lose its stability and quickly return to the previous state,and the contacts will be in contact again.For different kinds of diaphragms,the material and thickness of the diaphragm will affect its sudden jump and reduction temperature;For the same type of diaphragm,the sudden jump and recovery temperature will not reach the standard due to processing and assembly errors.Therefore,it is necessary to screen the temperature characteristics of the diaphragm before leaving the factory,and detect its jump and reduction temperature.This subject is dedicated to the establishment of a temperature protector diaphragm temperature characteristics screening system,which can conveniently and accurately detect the sudden jump and reduction temperature of the diaphragm.In order to achieve the goal of this subject,this paper designs a PC-based heating box temperature control and motor infrared detection screening system.This article analyzes the hardware construction of the system,the temperature simulation of the heating box,the design of the infrared detection circuit of the microcontroller,and the software design of the system.The main work content is divided into the following four parts:1.Control system hardware construction: Based on the analysis of the specific requirements and functional objectives of the temperature characteristics screening system,the overall design plan of the system is proposed,the hardware parameters are analyzed and the mechanical structure design is completed to complete the equipment selection,including heating box,PID Hardware equipment such as temperature controller,thyristor and microprocessor.2.Temperature simulation of the heating box: According to the structure of the heating box,the heat transfer analysis is carried out,and the temperature field of the heating box is simulated.Common numerical simulation methods and mesoscopic simulation methods are analyzed,and the heat transfer of the heating box is simulated using the method based on the coupled LBM(lattice Boltzmann)model,and the accuracy of the algorithm is verified through experiments.And using the simulation results,the point jump temperature measured by Pt100 is compensated according to the coordinate system,make the detected diaphragm jump temperature more accurate.3.Design of infrared sudden jump detection circuit based on single-chip microcomputer:According to the system requirements,it is necessary to detect the jump of the heating bimetallic diaphragm and record its temperature,so an infrared detection circuit based on single-chip microcomputer is designed.It uses the single-chip microcomputer to generate infrared to detect the bimetallic diaphragm,and uses whether the infrared signal can be received to determine whether the diaphragm jumps and to determine the jump position.And use the temperature measurement circuit composed of Pt100,differential circuit and AD conversion chip to read the jump temperature.Finally,the jump temperature is transmitted to the host computer system through the communication module.4.System software design: Programs for the main process of the temperature characteristic screening system,temperature control sub-process,temperature compensation,single-chip detection system,human-computer interaction interface,communication between upper and lower computers have been written.Finally,the software and hardware debugging work was completed,and on this basis,related experiments were carried out and the performance of the temperature characteristic screening system was verified.