Patent ID: 7467512
Filing Date: 2008-12-23
Classification: F01N,F02B,Y02A,Y02T

Abstract:
1. An exhaust gas purifying apparatus for an engine, comprising: an addition apparatus that adds a reducing agent of NOx to an exhaust gas from the engine; a storage tank that stores the reducing agent of NOx that is added to the exhaust gas by the addition apparatus or a precursor thereof in a state of an aqueous solution; a concentration sensor that detects a concentration of the reducing agent or the precursor contained in the aqueous solution of the reducing agent or the precursor that is stored in the storage tank; and a controller that generates an operation command to a predetermined object for being controlled related to purifying of the exhaust gas on the basis of the detected concentration which is the concentration of the reducing agent or the precursor detected by the concentration sensor, wherein the controller determines whether or not the aqueous solution of the reducing agent or the precursor in the storage tank is in a stationary state and, at a stationary time when it is determined to be in a stationary state, permits sensing of the concentration by the concentration sensor, while at a shaking time other than the stationary time, prohibits the sensing of the concentration by the concentration sensor, and wherein the concentration sensor detects the concentration of the reducing agent or the precursor only at the stationary time.