Selective catalytic reduction (SCR) system of vehicle and backflow flow measuring module and measuring method thereof

Abstract

The invention provides a backflow flow measuring module for a selective catalytic reduction (SCR) system of a vehicle. The backflow flow measuring module is used for measuring tail gas treating fluidflow which backflows from a supply unit of the SCR system to a fluid tank when the SCR system works. The measuring module is constructed to perform the following operation that a tail gas treating fluid in the supply unit is emptied so that the maximum air volume under 0-bar relative pressure can be achieved in the supply unit; then the tail gas treating fluid is introduced into the supply unit sothat conventional working pressure when the SCR system works is established in the supply unit; then the tail gas treating fluid in the supply unit is discharged naturally so that pressure in the supply unit can be released naturally, and meanwhile, pressure and elapsed time of pressure release of the supply unit are detected; and then based on the relationship between the pressure and the elapsed time of pressure release of the supply unit in the pressure release process, the tail gas treating fluid backflow flow when the SCR system works is determined.

Description

technical field [0001] The present application relates to an exhaust gas treatment liquid reflux flow measurement module and a reflux flow measurement method used in an SCR (Selective Catalytic Reduction) system of a vehicle, especially a diesel engine vehicle, and a vehicle SCR system including the measurement module. Background technique [0002] For aftertreatment of vehicle engine exhaust, SCR systems are employed. The SCR system can inject the exhaust gas treatment liquid (usually urea aqueous solution) into the exhaust gas, so as to reduce the amount of NOx in the exhaust gas by using the selective catalytic reduction method. [0003] The SCR system generally includes a supply unit for supplying the exhaust gas treatment liquid in the liquid tank to the injection unit. The supply unit is connected to the liquid tank via suction and return lines. When the SCR system is working, the supply unit draws the tail gas treatment liquid from the liquid tank through the suctio...

AI Technical Summary

Problems solved by technology

However, the resulting large return flow range will affect the relevant functions of the SCR system

For example, it will affect the exhaust gas treatment fluid CDM (consumption deviation monitoring) function, etc.

Such a large return flow range makes calibration and adjustment of these functions difficult, i.e. it is difficult to determine the appropriate calibration value to cover this large return flow range

In order to narrow this return flow range, the hardware design of the return throttling element can be changed, which will lead to an increase in cost

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