To utilize exhaust heat as effectively as possible while improving fuel economy.
This exhaust Ge device 10 of an engine 1 in which an NOx storage catalyst 18 is disposed in an exhaust passage 15 has a heat exchanger 30 with a heat storage material which recovers exhaust heat as an energy. The heat exchanger 30 includes: a heating section 33 for vaporizing a liquid exhaust heat collecting refrigerant Wm by heating the refrigerant by exhaust heat; a condensing section 37 for condensing the refrigerant Wm vaporized by the heating section 33 by exchanging heat with an engine refrigerant Wc and circulating the refrigerant to the heating section 33; and a heating promoting section 35 in which a heat storage material 36 is so disposed as to exothermically react to a part of the vaporized refrigerant Wm. When the temperature of the NOx storage catalyst 18 is equal to or below a predetermined temperature T1 which is positioned near the upper limit of the active temperature of the catalyst, the heat storage material 36 performs an exothermic reaction to the vaporized refrigerant Wm for heating the refrigerant in the heating promoting section 35. When the temperature exceeds the predetermined temperature T1, the exothermic reaction in the heating promoting section 35 is suppressed to cool the NOx storage catalyst 18.
TATEISHI TETSUYA
YASUTOMI KATSUAKI
IGAI TAKASHI
ICHIKAWA KAZUO
Masataka Otani
Jiro Higuchi