Abstract: A gas generator includes a housing main body made of metal, a holder assembly, and an igniter. The holder assembly includes a holder portion made of metal and a connector portion made of resin. The holder portion includes a first barrel portion and an annular projection. The connector portion includes a second barrel portion and a cylindrical portion. The cylindrical portion is inserted in the housing main body and externally attached to the first barrel portion. As a portion of the housing main body corresponding to the cylindrical portion is decreased in diameter, the cylindrical portion is compressed by being sandwiched between the portion of the housing main body decreased in diameter and the first barrel portion so as to seal a gap between the housing main body and the first barrel portion.

Abstract: An exhaust gas purifier is disposed in an exhaust gas passage of an engine, and includes: a DPF for capturing PM contained in exhaust gas; an SCR catalyst provided downstream of the DPF in a direction of flow of the exhaust gas, and for reducing NOx contained in the exhaust gas for purification in the presence of NH3; an injection unit provided between the DPF and the SCR catalyst, and for supplying urea to the SCR catalyst so as to supply NH3 to the SCR catalyst; and an AMOX provided downstream of the SCR catalyst in the direction of flow of the exhaust gas, and for removing NH3 having passed through the SCR catalyst. The DPF does not contain Pt or Pd, and contains Rh. The AMOX contains Pt.

Abstract: An exhaust gas purifier is disposed in an exhaust gas passage of an engine, and includes: a DPF for capturing PM contained in exhaust gas; an SCR catalyst provided downstream of the DPF in a direction of flow of the exhaust gas, and for reducing NOx contained in the exhaust gas for purification in the presence of NH3; an inj ection unit provided between the DPF and the SCR catalyst, and for supplying urea to the SCR catalyst so as to supply NH3 to the SCR catalyst; and an AMOX provided downstream of the SCR catalyst in the direction of flow of the exhaust gas, and for removing NH3 having passed through the SCR catalyst. The DPF does not contain Pt or Pd, and contains Rh. The AMOX contains Pt.

Abstract: A catalyst 20 provided for a filter body for combusting PM contains activated aluminas 21 and 22, active-oxygen-release materials 23 and 24, catalytic metal 25, and alkali earth metal 26. The alkali earth metal 26 is loaded on each of the activated aluminas 21 and 22, and the active-oxygen-release materials 23 and 24. A percentage by mass of the alkali earth metal 26, loaded on the active-oxygen-release materials 23 and 24, to the active-oxygen-release material is smaller than a percentage by mass of the alkali earth metal 26, loaded on the activated aluminas 21 and 22, to the activated alumina.

Abstract: A catalyst 20 provided for a filter body for combusting PM contains activated aluminas 21 and 22, active-oxygen-release materials 23 and 24, catalytic metal 25, and alkali earth metal 26. The alkali earth metal 26 is loaded on each of the activated aluminas 21 and 22, and the active-oxygen-release materials 23 and 24. A percentage by mass of the alkali earth metal 26, loaded on the active-oxygen-release materials 23 and 24, to the active-oxygen-release material is smaller than a percentage by mass of the alkali earth metal 26, loaded on the activated aluminas 21 and 22, to the activated alumina.