Development On Diesel Urea Concentration Sensor

With more attentions paid by people to the environment problems and more strict rulesand regulations created by government in countries all over the world, many new technologiesaimed at reducing the pollutant emissions have been investigated and applied in real life. Inthe field of diesel engine, people have invented the technology of select catalytic reduction, orSCR for short, to reduce the emission of nitrous oxides and particulate matter in the exhaustof the diesel engine. The system which uses this technology to reduce the exhaust of the dieselengine is called the SCR system. The SCR technology adopts a redox reaction between theAdBlue and the nitrous oxides in the exhaust of the diesel engine to reduce the nitrous oxides.The solution concentration of the AdBlue is a very important factor to ensure the reaction.Therefore, an AdBlue concentration sensor which can integrate into the SCR system isresearched and developed in this paper in order to make a real-time detection to the solutionconcentration of theAdBlue.For the research of the AdBlue concentration sensor, a NIR analysis technology to detectthe solution concentration of the AdBlue is introduced in this paper. Besides, the componentsin the optical system and the design of the optical system, the components in the electricalsystem and the design of the electrical system are also presented in the paper in detail. Finally,this paper introduces the integration and the package of the system, then to create theprototype of the sensor. Four aspects are mainly presented in this paper:Firstly,based on procedures to create work curves in the NIR absorption quantitativeanalysis method, we prepare standard solution sets and test solution sets in real life. By testingthese solutions,the relationship between the solution concentration and the output voltage isestablished. The relationship, namely work curves, is also the software system of our sensor.Secondly,on the establishment of the optical system, we choose the NIR LED as the lightsource of our sensor, optical filter as the spectral instrument and the InGaAs photodiode as theoptical detector, respectively. In addition, based on the theories of optical design and thereasonable and clever optical design, we create the optical system of our sensor.Thirdly,on the establishment of the electrical system, we design the electrical system onthe three aspects below: the driving circuit of the LED, the detection circuit of the detectioninstrument and the auxiliary circuit. According to the application,we select the appropriatefunction chips to control the LED and obtain the accurate detection. The examination to thesolution temperature is also included. We also draw the schematic diagram and PCB diagramin the professional software. Finally,on the structural design, we discuss both on the overall structure of the sensor andthe integration of the sensor on the urea tank in the SCR system. The design, integration andmounting mode of the various components in the sensor are described and the selection to thematerial of the various components is also introduced.