초록 ▼

An exhaust gas purifying device for an engine comprises an exhaust gas purifying catalyst arranged in the exhaust passage. The catalyst is capable of reducing NO.sub.X in the catalyst in the oxidizing atmosphere, and comprises a reducing agent adsorbent adsorbing a reducing agent in the inflowing ex

An exhaust gas purifying device for an engine comprises an exhaust gas purifying catalyst arranged in the exhaust passage. The catalyst is capable of reducing NO.sub.X in the catalyst in the oxidizing atmosphere, and comprises a reducing agent adsorbent adsorbing a reducing agent in the inflowing exhaust gas therein when the pressure in the adsorbent becomes higher, and desorbing the adsorbed reducing agent therefrom when the pressure in the adsorbent becomes lower. An exhaust gas control valve is disposed in the exhaust passage downstream of the catalyst. When both the engine load and the engine speed are low, the opening of the valve is made smaller to increase the pressure in the catalyst. At this time, hydrocarbon is fed to the catalyst, and is then adsorbed in the catalyst. When the engine load or the engine speed becomes high, or the cumulative amount of hydrocarbon fed to the catalyst becomes larger than a predetermined amount, the valve is made fully open to reduce the pressure in the catalyst. At this time, the adsorbed hydrocarbon is desorbed from the catalyst, and then reduces NO.sub.X in the catalyst.

대표청구항 ▼

[ We claim:] [1.] An exhaust gas purifying device for an engine having an exhaust passage, comprising:an exhaust gas purifying catalyst arranged in the exhaust passage, the catalyst capable of reducing NO.sub.X in the catalyst in the oxidizing atmosphere, and comprising a reducing agent adsorbent ad

[ We claim:] [1.] An exhaust gas purifying device for an engine having an exhaust passage, comprising:an exhaust gas purifying catalyst arranged in the exhaust passage, the catalyst capable of reducing NO.sub.X in the catalyst in the oxidizing atmosphere, and comprising a reducing agent adsorbent adsorbing a reducing agent in the inflowing exhaust gas therein when the pressure in the adsorbent becomes higher, and desorbing the adsorbed reducing agent therefrom when the pressure in the adsorbent becomes lower;a reducing agent feeding means for feeding a reducing agent to the catalyst; andpressure control means for controlling the pressure in the catalyst,wherein the pressure control means increases the pressure in the catalyst to adsorb the reducing agent in the catalyst, and reduces the pressure in the catalyst to desorb the adsorbed reducing agent from the catalyst, andwherein NO.sub.X is reduced by the reducing agent in the catalyst.