The Design Of Five Team Automobile Exhausts Gas Analyzer Measuring System

The civilian vehicle growth,particularly in the fast-growing private cars has brought great convenience to people's daily life,but also leads to a serious environmental problems arising from its exhaust and it becomes a hazard now.Scientific analysis discovers that vapour,O₂,H₂,N₂,CO₂,CO,hydrocarbons,NO_X,SO₂,particulate matter etc are all included in the automobile exhaust.Those ingredients harmful to human beings and impacting on the natural growth are called pollutants,such as CO₂,CO, hydrocarbons,NO_X,SO₂,particulate matter.According to statistics,one car exhaust emission in a year is larger 3 times than the weight of its own.In order to control motor vehicle emissions and improve the ambient air quality, related departments approve of the latest standardin March 2,2005.It formulates fire-engine vehicle exhaust emission limits and measuring methods in idling and high Idling conditions. There is still a big gap in technical level of automobile tail gas analyzer between China and foreign.It is mainly manifested in these aspects as following:the basic research of analytical theory of infrared gas is still imperfect,not systematized and not in-depth, products subject to a more serious impact on the environment,poor reliability,low levels of automation,the absence of an independent intellectual property rights for some high-performance products and so on.Vehicle exhaust analyzer measurement system in this subject starts from the concrete realization of the program,making a specific design by introducing to the history and current situation of domestic and foreign gas analyzer application development,stating to thermopile sensor knowledge and explaining to related theory about measurement principles of electrochemical measuring principle.This automobile exhaust analyzer can analyze 5 gases in tail gas.The principle of regardless of infrared light absorption is applied in measuring CO₂,CO and hydrocarbons.Electrochemical cell theory is adopted in measuring in nitric oxides(NO) and O₂.Advanced filter technology,comparative measuring methods are also used in measuring.So the analyzer has excellent anti-jamming performance.The system still is equipped with temperature sensors which can measure the lubricant temperature at the same time of measuring tail gas.It also adopts microprocessor control methods and has large-screen liquid crystal display and Chinese characters mini-printers.Chinese language operating interface is simple by using one key to control.Data communications with computer can realize.It can transmit on-site measurements through the serial port for data processing.Chinese-panel mini-printers with the instrument can print measurement results and measurement date to save as information.The paper analyzes the system's hardware and software design process,measurement,measuring principle and sensor selection in detail.