Exhaust gas purifying apparatus for internal combustion engine

Abstract

An object of the present invention, in an internal combustion engine equipped with a moisture adsorbent and a NOx adsorbent in series in order from the upstream side of an exhaust passage, is to provide an exhaust gas purifying apparatus for the internal combustion engine which can successfully prevent an adsorption capability of NOx from being inhibited by moisture and is capable of maintaining the NOx adsorption capability of the NOx adsorbent adequately. A main exhaust passage 14 through which exhaust gas exhausted from an internal combustion engine 10 flows is provided. A bypass passage 20 bypassing the main exhaust passage 14 is provided. A moisture adsorbent 24 and a NOx adsorbent 28 are provided in the bypass passage 20 in series in order from a side closer to the upstream connecting portion 20 a . A switching valve 22 is controlled to prevent the exhaust gas from flowing into the NOx adsorbent 28 when it is judged that the desorption of the moisture from the moisture adsorbent 24 is started.

1 . An exhaust gas purifying apparatus for an internal combustion engine, the apparatus comprising:
 a main exhaust passage through which exhaust gas exhausted from the internal combustion engine flows;   a bypass passage branching off from the main exhaust passage at an upstream connecting portion connected to the main exhaust passage while merging again with the main exhaust passage at a downstream connecting portion provided downstream of the upstream connecting portion;   flow path switching means that is capable of switching a flow target into which the exhaust gas flows between the main exhaust passage and the bypass passage;   a moisture adsorbent that is disposed in the bypass passage and has a function of adsorbing moisture;   a NOx adsorbent that is disposed in the bypass passage at a downstream side of the moisture adsorbent as for an exhaust gas flow in a state where the moisture adsorbent adsorbs the moisture and has a function of adsorbing NOx;   moisture desorption judgment means for judging whether desorption of the moisture from the moisture adsorbent is started; and   flow path control means for controlling the flow path switching means to prevent the exhaust gas from flowing into the NOx adsorbent when it is judged that the desorption of the moisture from the moisture adsorbent is started.   
   
   
       2 . The exhaust gas purifying apparatus for the internal combustion engine according to  claim 1 ,
 wherein the moisture desorption judgment means judges whether the desorption of the moisture is started on the basis of a temperature of the moisture adsorbent.   
   
   
       3 . An exhaust gas purifying apparatus for an internal combustion engine, comprising:
 a main exhaust passage through which exhaust gas exhausted from the internal combustion engine flows;   a bypass passage branching off from the main exhaust passage at an upstream connecting portion connected to the main exhaust passage while merging again with the main exhaust passage at a downstream connecting portion provided downstream of the upstream connecting portion;   a flow path switching device that is capable of switching a flow target into which the exhaust gas flows between the main exhaust passage and the bypass passage;   a moisture adsorbent that is disposed in the bypass passage and has a function of adsorbing moisture;   a NOx adsorbent that is disposed in the bypass passage at a downstream side of the moisture adsorbent as for an exhaust gas flow in a state where the moisture adsorbent adsorbs the moisture and has a function of adsorbing NOx;   a moisture desorption judgment device for judging whether desorption of the moisture from the moisture adsorbent is started; and   a flow path control device for controlling the flow path switching device to prevent the exhaust gas from flowing into the NOx adsorbent when it is judged that the desorption of the moisture from the moisture adsorbent is started.