EXHAUST GAS PURIFICATION SYSTEM AND METHOD FOR CONTROLLING THE SAME

摘要

An exhaust gas purification system capable of preventing clogging of a reducing agent injection valve due to solidified urea aqueous solution to prevent a decrease in the exhaust gas purification efficiency of an internal-combustion engine. The exhaust gas purification system includes a diesel particulate filter, a reducing agent injection valve and an SCR catalyst in this order from the exhaust upstream side. A condition satisfaction determination section determines whether or not urea aqueous solution is likely to be solidified when detecting that an ignition switch is turned off, and an internal-combustion engine stop prevention section prevents the internal-combustion engine from being stopped, based on a determination by the condition satisfaction determination section.

主权项

1. An exhaust gas purification system comprising:
a diesel particulate filter (DPF) for collecting exhaust particles contained in exhaust gas to be exhausted; a reducing agent injection valve for injecting urea aqueous solution as a reducing agent in the exhaust gas; a selective catalytic reduction (SCR) catalyst for using the urea aqueous solution to purify nitrogen oxides (NOx) contained in the exhaust gas, in this order from the exhaust upstream side; and an engine controller including a microcomputer configured to predict whether or not the urea aqueous solution will be solidified when an internal-combustion engine is stopped or when it is assumed that the internal-combustion engine is stopped while the internal-combustion engine is operating and notify an operator of the internal-combustion engine when predicting that the urea aqueous solution will be solidified.