| 摘要 |
PURPOSE:To protect copper-zeolite catalyst, by switching the introduction of exhaust gas from a catalyst layer consisting of copper and zeolite when the temp. of the exhaust gas is lower to a catalyst layer consisting of ternary catalyst when the temp. is higher. CONSTITUTION:The exhaust gas from a combustion chamber 11 of an engine 1 is introduced to a first catalyst layer 3 through a switching valve 22 to purify NOX, CO and HC with the copper-zeolite catalyst, when the temp. of the exhaust gas is lower. When the higher temp. (e.g. 680 deg.C) of the exhaust gas is detected with a temp. sensor 20, the exhaust gas is introduced to a second catalyst layer 4 by changing the switching valve 22 with an EFI computer 5 to purify NOX, CO and HC with the ternary catalyst carrying Pt and Rh on alumina carrier. Thereby, the copper-zeolite catalyst can be protected over a long period. |
