Ammonia gas jetting amount control method based on SCR system

Abstract

The invention discloses an ammonia gas jetting amount control method based on an SCR system. The ammonia gas jetting amount control method based on the SCR system comprises the steps that the model conversion efficiency of nitric oxides NOx is obtained according to ammonia gas NH3 stored in the SCR system; the target conversion efficiency of the nitric oxides NOx is obtained according to the flowof the nitric oxides NOx on the air inlet side of the SCR system; the actual conversion efficiency of the nitric oxides NOx is obtained; the efficiency deviation is obtained according to the actual conversion efficiency and the target conversion efficiency; sum calculation is conducted on the model conversion efficiency and the efficiency deviation to obtain the demand conversion efficiency; and the demand jetting amount of the ammonia gas NH3 is obtained according to the demand conversion efficiency. According to the ammonia gas jetting amount control method based on the SCR system, the target conversion efficiency capable of balancing emission of the nitric oxides NOx and the leakage amount of the ammonia gas NH3 is proposed, efficiency compensation is conducted on the model conversion efficiency through the deviation efficiency between the target conversion efficiency and the actual conversion efficiency, therefore, precise control over the demand jetting amount of the ammonia gas NH3 is achieved, and the problem of leakage pollution generated due to the fact that the ammonia gas NH3 jetting amount is too high is avoided.

Description

technical field [0001] The invention relates to the technical field of automobiles, in particular to an SCR system-based ammonia injection quantity control method. Background technique [0002] In order to make the diesel engine meet the National VI emission requirements, a Selective Catalytic Reduction (SCR) system is generally used to control the emission of the diesel engine. Among them, the SCR system uses ammonia (NH 3 ) to remove nitrogen oxides (NO X ) is reduced to pollution-free nitrogen and water. But since NH 3 Injection amount affects NO X Reduction efficiency, too little NO injection X The reduction efficiency is low, which cannot satisfy the emission; and the excessive injection amount will cause NH 3 Leakage will also cause pollution, so NH 3 Injection quantity control is an important strategy for SCR system calibration. In the prior art, in order to improve the reaction efficiency of nitrogen oxides, NH 3 Excessive injection volume, resulting in NH ...

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Problems solved by technology

But since NH 3 Injection amount affects NO X Reduction efficiency, too little NO injection X The reduction efficiency is low, which cannot satisfy the emission; and the excessive injection amount will cause NH 3 Leakage will also cause pollution, so NH 3 Injection volume control is an important strategy for SCR system calibration

In the prior art, in order to improve the reaction efficiency of nitrogen oxides, NH 3 Too much injection, resulting in NH 3 Pollution

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