Vehicle-mounted SCR metering and ejecting system taking exhaust gas temperature as variable

Abstract

The invention relates to a vehicle-mounted SCR metering and ejecting system taking exhaust gas temperature as variable. The system is characterized in that a precision thermoelectric couple is connected with a temperature control unit through a wire and installed on an expansion pipe at the inlet end of an SCR rear processor, an electromagnetic metering diaphragm pump is connected on a pipeline, and a pressure reducing valve and a urea reducing agent filter are arranged between the electromagnetic metering diaphragm pump and a urea reducing agent tank; a one-way valve is arranged at the outputend of the electromagnetic metering diaphragm pump; and a urea reducing agent nozzle is arranged at the front end of the SCR rear processor, and a one-way valve, a compressed air filter, a pressure reducing valve, a pressure gauge and a valve are connected between a gas liquid mixing unit with two cavities and an air power source. By adopting the temperature measured by the thermoelectric couple,the temperature parameter is taken as the variable, and the electromagnetic metering diaphragm pump is started through an intelligent PID controller and a self-programming computer program, so that the urea reducing agent is completely atomized in the gas liquid mixing unit with the two cavities to achieve the purpose of eliminating NOX; and the cost of the system is equivalent to one fourth to one third of that of an imported system, the reliability is high, and the industrial application is realized.

Description

Technical field: [0001] The invention relates to a vehicle-mounted SCR metering injection system with exhaust temperature as a variable, which is applied in the automobile engine industry and meets the environmental protection auxiliary requirements above Euro 4. Background technique: [0002] The harmful components in automobile engine exhaust are mainly PM, NOx, HC and CO. In the past 2 to 3 years, low-emission engines have become an ideal that people debate, care about, and even aspire to achieve. [0003] The US Environmental Protection Agency (EPA) 2007 emissions regulations require automakers to reduce both particulate (PM) and nitrogen oxide (Nox) pollutants in exhaust gases. This requires considerable skill, and there are no shortcuts to solving this problem. According to the traditional method, the reduction of one kind of pollution will inevitably lead to the increase of another kind of pollution. Automakers appear to be in trouble. [0004] Under the pressure ...

AI Technical Summary

Problems solved by technology

However, when the engine is running at a cold start, idling or insufficient combustion stage, the temperature is usually kept below 150°C. At this time, more HC and PM can be generated. These components can block the microscopic pores of the SCR catalyst, resulting in SCR conversion efficiency drops

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