Exhaust gas purification device for an engine
    7.
    发明授权
    Exhaust gas purification device for an engine 失效
    发动机废气净化装置

    公开(公告)号:US5746052A

    公开(公告)日:1998-05-05

    申请号:US525892

    申请日:1995-09-08

    摘要: In the present invention, the exhaust gas from the engine is divided into a first and a second branch exhaust passages after it passes through a three-way reducing and oxidizing catalyst, and the two branch exhaust passages merge into an exhaust gas outlet passage. In the first branch exhaust passage, an oxidizing catalyst is disposed, and in the exhaust gas outlet passage, a denitrating and oxidizing catalyst is disposed. NO.sub.x in the exhaust gas from the engine is all converted to N.sub.2 and NH.sub.3 by the three-way reducing and oxidizing catalyst and a part of the NH.sub.3 generated by the three-way catalyst flows into the first branch exhaust passage and is converted to NO.sub.x again by the oxidizing catalyst. The amount of NO.sub.x produced by the oxidizing catalyst and the amount of NO.sub.x flowing through the second branch exhaust passage is determined by the flow distribution ratio of the first and the second branch exhaust passages. In this invention, the flow ratio is determined in such a manner that the amount of the NO.sub.x produced by the oxidizing catalyst and the amount of the NH.sub.3 passing through the second branch exhaust passage are stoichiometric to produce N.sub.2 and H.sub.2 O. Therefore, when these exhaust gases flow into the denitrating and oxidizing catalyst after they mix with each other in the exhaust gas outlet passage, all the NO.sub.x and the NH.sub.3 are converted to N.sub.2 and H.sub.2 O by the denitrating and oxidizing catalyst without producing any surplus NO.sub.x or NH.sub.3.

    摘要翻译: 在本发明中,来自发动机的废气在通过三通还原氧化催化剂后被分成第一和第二分支排气通道,两个分支排气通道合流到废气出口通道中。 在第一分支排气通道中设置氧化催化剂,并且在排气出口通道中设置脱硝和氧化催化剂。 来自发动机的废气中的NOx通过三元还原氧化催化剂全部转化为N 2和NH 3,并且由三元催化剂产生的一部分NH 3流入第一分支排气通道并再次转化为NOx 通过氧化催化剂。 由氧化催化剂产生的NOx的量和流过第二分支排气通道的NOx的量由第一和第二分支排气通道的流量分配比确定。 在本发明中,流量比以如下方式确定:氧化催化剂产生的NOx的量和通过第二分支排气通道的NH 3的量是化学计量的,以产生N 2和H 2 O. 因此,当这些废气在废气出口通道中彼此混合后流入脱硝和氧化催化剂时,所有的NOx和NH 3都被脱硝和氧化催化剂转化为N 2和H 2 O,而不产生任何剩余的NOx或 NH3。

    Exhaust gas purification device for an engine
    10.
    发明授权
    Exhaust gas purification device for an engine 失效
    发动机废气净化装置

    公开(公告)号:US5740669A

    公开(公告)日:1998-04-21

    申请号:US559107

    申请日:1995-11-16

    摘要: In the present invention, a NO.sub.x absorbent is used for removing the NO.sub.x in the exhaust gas. The NO.sub.x absorbent absorbs NO.sub.x in the exhaust gas when the air-fuel ratio of the exhaust gas is lean, and releases the absorbed NO.sub.x and reduces it to nitrogen when the air-fuel ratio of the exhaust gas is rich or stoichiometric. To prevent the NO.sub.x absorbent from being saturated with the absorbed NO.sub.x, the NO.sub.x absorbent must be regenerated periodically by causing the NO.sub.x in the absorbent to be released and reduced. However, it is found that when the regenerating process by supplying a rich air-fuel ratio exhaust gas to the NO.sub.x absorbent is carried out at high NO.sub.x absorbent temperature, a part of NO.sub.x flows out from the NO.sub.x absorbent at the beginning of the regenerating process without being reduced. In the present invention, this outflow of NO.sub.x is suppressed by, for example, carrying out the regenerating process only when the temperature of the NO.sub.x absorbent is lowered to a predetermined temperature. This predetermined temperature is set low enough to ensure that the amount of the outflow of NO.sub.x is minimized.

    摘要翻译: 在本发明中,使用NOx吸收剂除去废气中的NOx。 当排气的空燃比稀薄时,NOx吸收剂吸收废气中的NOx,并且当排气的空燃比浓或化学计量时,释放吸收的NOx并将其还原成氮。 为了防止NOx吸收剂被吸收的NOx饱和,NOx吸收剂必须通过使吸收剂中的NOx释放和还原而周期性地再生。 然而,发现当在高NOx吸收温度下进行通过向NOx吸收剂供给浓空燃比废气的再生过程时,在再生过程开始时,部分NOx从NOx吸收剂流出 没有减少 在本发明中,只有当NOx吸收剂的温度下降到规定温度时,例如仅进行再生处理,可以抑制NOx的流出。 该预定温度被设定得足够低以确保NOx的流出量最小化。