EXHAUST GAS PURIFICATION DEVICE FOR INTERNAL COMBUSTION ENGINES

摘要

Disclosed is an exhaust gas purification device for internal combustion engines that can improve the NOx purification rate by preventing the release of NOx that has not been purified by a selective reduction type catalyst, regardless of whether the selective reduction type catalyst is active or inactive. The device is equipped with a NOx absorption material (25) that temporarily adsorbs NOx, a selective reduction type catalyst (40) that is provided downstream from the NOx adsorption material in an exhaust passage (15) and that selectively reduces the NOx contained in the exhaust gas, a urea solution addition valve (70) that supplies ammonia as a reducing agent to the selective reduction catalyst, and a burner (20) that removes the NOx adsorbed onto the NOx adsorption material. The device is constructed to adjust the purification rate of the selective reduction type catalyst and/or the amount of NOx removal by the burner (20) in order to limit the release of NOx to the outside when the NOx is removed from the NOx adsorption material.