System Design Of Bench Type Oil Contamination Detector

In order to reduce the hydraulic system failure caused by particle pollutants in oil,based on the principle of photoresistance method,this paper is committed to designing a desktop oil pollution detector with low cost,high precision and strong reliability.The main work contents are as follows:Analysis of the current typical particle pollutants detection methods and compare their advantages and disadvantages,combined with the domestic and foreign research status,determine the necessity of designing an oil pollution degree detector based on the principle of photoresistance method,elaborated the purpose and significance of the research,determine the main research content of this paper.First,the overall design of the instrument was developed.According to the current mainstream oil pollution grade standard and the functional requirements of the oil pollution degree detector,the performance index of the instrument is determined.Based on the optical resistance method,the design of the instrument is divided into sampling,particle detection,signal processing,control and peripheral five modules,and from the mechanical structure and hardware circuit and software system two aspects,complete the overall design of the instrument.In terms of mechanical structure and hardware circuit,this paper mainly does the following work: according to the function of each module of the instrument to the mechanical structure of the whole box design and draw a 3D model;According to the relevant performance index of the instrument,the size of the detection area was determined,the sensor was selected,and the light source driving circuit was built.The signal processing flow is designed,including: I-V conversion circuit,filter circuit,differential amplifier circuit and comparison circuit;The structure of the sampling pump is designed,its 3D model is drawn and the device selection is carried out,and the peripheral control circuit is built.The structure of the air pressure chamber is designed and 3D modeling is carried out to realize the built-in magnetic stirring function.The suitable pneumatic components are selected to form the positive and negative pressure gas path,and the solenoid valve control circuit is built.The precautions and countermeasures of antijamming in circuit design are analyzed and summarized.Solid Works software is used to integrate the 3D model of each module into the instrument box and allocate the space layout reasonably.In the aspect of software system,this paper mainly does the following work: design the main program logic of the software,generally divided into upper computer and lower computer two parts,select the touch screen and STM32 chip respectively as the upper computer and lower computer;Designed the UI interface of the upper computer,mainly responsible for humancomputer interaction function,sending operation instructions and reading test results through the touch screen of the upper computer;In Keil u Vision development environment,C language is used to write the bottom code,the lower computer controls the running of the bottom code,according to the instructions of the upper computer to drive the hardware to carry out corresponding actions,to complete the expected function.In order to test the research results,build an experimental platform and configure different specifications of standard solution,the instrument experiments,test the function of different modules and analysis of the experimental results,according to NAS1638,ISO4406 and other oil pollution grade standards for threshold calibration,testing instrument measurement error,particle resolution and flow limit indicators.At last,it summarizes the research emphases and difficulties of oil pollution detector,and puts forward the prospect of future work.