Closed loop control method for SCR (Selective Catalyst Reduction) system of all-working-condition diesel engine

Abstract

The invention discloses a closed loop control method for an SCR (Selective Catalyst Reduction) system of an all-working-condition diesel engine. The method is carried out according to the following steps of: (1) establishing a novel three-dimensional matrix of the adding amount of reducing agent for the SCR system based on exhaust temperature and exhaust backpressure of the all-working-condition diesel engine; and (2) forming a precise control mode of a closed loop of the SCR system of the all-working-condition diesel engine by utilizing a nitrogen oxide sensor and a PID (Proportion Integration Differentiation) controller. By using the closed loop control method for the SCR system of the all-working-condition diesel engine in the invention, the acquisition of working-condition parameters of the diesel engine can not depend on an electronic control unit (ECU) of the diesel engine, the technical obstacle that the current home and abroad SCR systems are only suitable for electrically controlling the diesel engine is broken through, and an approach for reducing the discharging amount of NOx is provided for vehicles assembled with light, middle and heavy non-electric control diesel engines.

Description

technical field [0001] The invention belongs to the technical field of diesel engine tail gas nitrogen oxide emission pollution control, and further relates to a closed-loop control method for an SCR system of a diesel engine under all working conditions based on exhaust temperature and exhaust back pressure. Background technique [0002] Energy saving and environmental protection are two important themes in the field of industrial technology in our country and the world today. Nitrogen oxides (NO x ) is the main pollutant emitted by diesel engines, and the use of diesel engine internal purification technology has been unable to meet the current and future implementation of emission regulations. Therefore, the adoption of diesel engine exhaust post-treatment purification technology is a necessary means to meet the increasingly stringent emission regulations (mainly National IV and above emission regulations). Combined with my country's national conditions and the status qu...

AI Technical Summary

Problems solved by technology

Its disadvantages are: (1) When the internal or external environment of the SCR post-treatment system, such as catalyst performance, temperature, oil quality and other factors change, it cannot be fed back to the system in time to adjust the dosage of reducing agent, resulting in system control Low accuracy; (2) For non-electronically controlled diesel engines, the speed and load parameters of the diesel engine cannot be obtained, and the SCR system cannot control the amount of reducing agent

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