Reductant injection control device in scr system

Abstract

The invention discloses a reductant spraying control device in a selective catalytic reduction (SCR) system. The reductant spraying control device comprises a liquid storage tank, an airflow pipeline, a liquid flow pipeline, a control unit, a nozzle and a vent pipe, wherein the control unit controls the delivery of compressed air and reductant in the airflow pipeline and the liquid flow pipeline. The airflow pipeline is communicated with an air source, the liquid flow pipeline is communicated with the liquid storage tank, the nozzle is a vacuum generator nozzle, and the nozzle is communicated with the airflow pipeline and the liquid flow pipeline. When the compressed air in the airflow pipeline passes by the nozzle, negative pressure is produced in the liquid flow pipeline, and the reductant spraying control device uses the pressure difference formed when the reductant and the compressed air pass by the vacuum generator nozzle as motive force to deliver reductant. The reductant spraying control device has the advantages that structure is simplified, cost is reduced, the reductant is avoided from crystallizing and blocking the spraying pipeline, and reliability is improved.

Description

technical field [0001] The invention relates to an SCR injection system in the aftertreatment of motor vehicle exhaust, in particular to a reducing agent injection control device in the SCR system for diesel vehicle exhaust treatment. Background technique [0002] As the society's requirements for environmental protection are getting higher and higher, the country's environmental protection is getting stronger and stronger. The relevant state departments have issued relevant policies on motor vehicle emissions, especially the implementation of the "National IV Standard", which has a strong impact on motor vehicle emissions. Emission control is becoming more stringent, and it is necessary to further reduce 30% to 50% of pollutants on the basis of meeting the "National III Standard" to meet the standard. At present, some cities in my country have begun to implement the "National IV Standard" tail gas emission policy. [0003] It is known that Selective Catalytic Reduction (SCR)...

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Problems solved by technology

[0004] However, the control system of the existing SCR motor vehicle exhaust after-treatment technology is relatively complicated, and basically all need to rely on a power source (such as a diaphragm pump or an electromagnetic pump) to provide the delivery power of the reducing agent. In this case, the reducing agent in the urea tank is sprayed into the exhaust pipe through the atomizing nozzle to perform catalytic reduction treatment on the exhaust gas in the exhaust pipe. However, the structure of this control system is complex and the cost is high. More, the hidden danger of failure is also greater

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