A correction system and method for scr ammonia storage model

Abstract

The invention discloses a correction system and method for an SCR ammonia storage model. The system includes a DOC catalytic converter, an SCR catalytic converter, a urea tank and a controller, and the outlet end of the DOC catalytic converter is connected to the inlet end of the SCR catalytic converter. , the connection between the DOC catalytic converter and the SCR catalytic converter is provided with a urea nozzle, and the urea tank is connected to the urea nozzle through a urea pump; the SCR catalytic converter is provided with a temperature sensor and NO X sensor, the temperature sensor and the NO X The data output end of the sensor is connected with the data input end of the controller, and the control signal output end of the controller is connected with the control signal input end of the urea pump. The method of the invention can correct the target ammonia storage amount of the SCR according to the temperature change inside the SCR, and can accurately correct the ammonia storage amount in the real-time process, thereby making the urea injection amount more accurate.

Description

technical field [0001] The invention belongs to the technical field of after-treatment of automobile exhaust, and in particular relates to a correction system and method for an SCR ammonia storage model. Background technique [0002] At present, Urea-SCR technology is considered to reduce the NO X The most effective method of emission is to spray urea solution with a mass fraction of 32.5% into the exhaust pipe through the urea injection system, and it needs to be converted into NH through the process of bumping, evaporation, hydrolysis, and pyrolysis. 3 , and then react with NOx to reduce the exhaust NOx emission of vehicle diesel engine. [0003] With the increasingly stringent emission regulations, the NOx emission limit is getting lower and lower, so the aftertreatment system needs a more precise urea injection control strategy to achieve high NOx conversion efficiency and low NH 3 Give way. In the existing urea injection control process, the temperature and space vel...

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Problems solved by technology

[0004] The existing technical solutions have a method for correcting the injection quantity specifically for transient working conditions, but they are not very accurate and the correction effect is not good. For example, Patent No. CN106837488B "A Urea Injection Control Method, Device and SCR System", calculates the SCR catalytic converter If the current temperature is in the first preset temperature area, the current urea injection amount is corrected according to the difference between the actual ammonia storage amount and the saturated ammonia storage amount of the SCR catalyst under the current working condition; if the current temperature is in the In the second preset temperature zone, the current urea injection amount is corrected according to the change of NOx conversion efficiency

The above method only makes simple corrections to the transient process, and cannot accurately correct the ammonia storage capacity, and cannot achieve high NOx conversion efficiency and low NH 3 Give way

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