| 摘要 |
PROBLEM TO BE SOLVED: To efficiently purify exhaust gas, while activating the downstream side catalyst so as to accelerate the chemical reaction by arranging plural catalyst in series in an exhaust passage of an engine, and arranging a heat accumulator between the upstream side catalyst and the downstream side catalyst. SOLUTION: An upstream side catalyst structure 71 of an exhaust gas purifying device 7 having a heat accumulator is formed of a NOx reduction catalyst 71a and a heat accumulator 71b arranged in rear of this NOx reduction catalyst 71a, and a downstream side catalyst structure 72 thereof has the NOx reduction catalyst 72a. The heat accumulating material forming the heat accumulator 71b is selected from among the metal material to be melted within the activating temperature area of the downstream side reduction catalyst 72a. With this structure, when the temperature of the exhaust gas G rises, the heat accumulating material is melted, and temperature of the exhaust gas G is lowered by the heat absorption of the melting heat. When the temperature of the exhaust gas G is lowered, temperature of the exhaust gas G is raised by discharging the heat of solidification so as to maintain a prolonged period, in which the temperature of the exhaust gas G exists within the activating temperature area of the downstream side catalyst 72a, long. |
