Gas-assisted urea injection system with mixing tube heating method adopted

Abstract

The invention discloses a gas-assisted urea injection system with a mixing tube heating method adopted, and belongs to the technical field of design of an automobile urea injection system. The gas-assisted urea injection system comprises a urea box (1), a urea box temperature and liquid level sensor (2), a heating control valve (6) and a heating water pipe (10), wherein the heating control valve (6) and the heating water pipe (10) are used for exchanging heat of the urea box (1). The gas-assisted urea injection system is characterized in that a urea metering valve (5) which is separated from a nozzle (4) is installed at the bottom of the urea box, a mixing cavity (3) is connected with the lower end of the urea metering valve (5), one end of the mixing cavity (3) is in pipeline connection with an air pipe (8) through a gas control valve (7), and the other end of the mixing cavity (3) is in pipeline connection with the nozzle (4) through a heating mixing tube (9). The gas-assisted urea injection system removes rigorous requirements for an air exhaust pipeline in the hydrolytic process of a urea solution, is simple in structure, facilitates overall arrangement, reduces crystallization risks of the urea solution, improves system reliability, breaks the situation that international suppliers monopolize, and fully plays technology and market competitiveness of independent products.

Description

Technical field: [0001] The invention belongs to the technical field of vehicle urea injection system design, and in particular relates to an air-assisted urea solution that cancels the hydrolysis process of liquid urea solution in the exhaust pipe and heats the urea solution before entering the exhaust pipe to complete the hydrolysis process. Injection system. Background technique: [0002] Compared with the national III emission regulations, the limits of exhaust pollutants (mainly particles and nitrogen oxides) from diesel engines are much lower in the national IV and national V emission regulations. It is difficult to reduce the above two exhaust pollutants in the engine at the same time, so that the engine emissions can meet the requirements of the National IV and National V emission regulations. Therefore, the SCR system has become one of the strategies to meet the National IV and National V emission regulations. It can effectively reduce the content of nitrogen oxide...

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Problems solved by technology

[0003] At present, the mature urea liquid injection systems are all produced by foreign companies, some adopt direct injection technology, and some use air-assisted injection technology, all of which require the urea aqueous solution to complete its hydrolysis and release ammonia in the exhaust pipe. Therefore, , the system has strict requirements on the exhaust temperature, the distance from the position of the nozzle to the inlet of the catalyst, and it is not easy to arrange the structure of the vehicle; at the same time, the hydrolysis of the urea solution in the exhaust pipe is easy to produce urea crystals, which affects the exhaust back pressure and engine performance

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