CONTROL TECHNIQUES OF EXHAUST PURIFICATION SYSTEM AND EXHAUST PURIFICATION SYSTEM

摘要

To provide an exhaust purifying system and a method for controlling the exhaust purifying system that avoid occurrence of clogging, breakage, or the like of a reducing agent injection valve caused by the solidification of a reducing agent and prevent reduction in the efficiency of reducing agent recovery processing and exhaust gas purification.;An exhaust purifying system and a method for controlling the exhaust purifying system according to an aspect of the present invention is configured to detect the injection valve temperature of the reducing agent injection valve according to detection of turn-off of an ignition switch for stopping the internal combustion engine or detection of an injection stop of the reducing agent injection valve, whichever is earlier, calculate the waiting time until reducing agent recovery processing starts based on the injection valve temperature, and permits the reducing agent recovery processing under condition of the detection of turn-off of the ignition switch and an elapse of the waiting time.

主权项

1. An exhaust purifying system including, sequentially from an exhaust upstream side, a diesel particulate filter that collects exhaust particulate in exhaust gas of an internal combustion engine, a reducing agent supply apparatus that supplies and injects an aqueous urea solution as a reducing agent to the exhaust gas by supplying the aqueous urea solution from a storage tank to a reducing agent injection valve and, when stopping the internal combustion engine, recovers the aqueous urea solution in a supply path to the storage tank, and a selective catalytic reduction catalyst that purifies NOx in the exhaust gas using the aqueous urea solution, the exhaust purifying system comprising:
a control apparatus including
a waiting time calculation unit that detects an injection valve temperature of the reducing agent injection valve according to detection of turn-off of an ignition switch for stopping the internal combustion engine or detection of an injection stop of the reducing agent injection valve, whichever is earlier, and calculates a waiting time until reducing agent recovery processing starts based on the injection valve temperature; anda reducing agent recovery processing permission unit that permits the reducing agent recovery processing under condition of the detection of turn-off of the ignition switch and an elapse of the waiting time.