A Study on Preventing UREA Back Flow by Blocked Dosing Nozzle for SCR System

摘要

Diesel engine vehicles that have to reduce NO_x of exhaust gas for strictness emission regulation are using a SCR system. In the case that the vehicle equipped the SCR system of B company, the name of main process returning all urea back to the tank when engine turn off is AFTERRUN. It will be a problem if urea flows backward from the tank by blocked dosing nozzle when AFTERRUN process is finished. In this study defines the main factor of nozzle blocking phenomenon and makes sure that solutions have an effect to prevent nozzle blocking and urea back flow by testing on commercial vehicles. Throughout the testing on a bus and a truck, it has a conviction that solutions can be used on vehicles which have variable SCR layouts.