Hitachi, Ltd.

Babcock-hitachi Kabushiki Kaisha

Noriko Watanabe

Toshio Ogawa

Osamu Kuroda

Takeshi Atago

Akio Honji

Minoru Osuga

Masakatsu Fujishita

Akira Kato

Hisao Yamashita

Hiroshi Miyadera

Shinpei Matsuda

Hiroshi Kawagoshi

Takahiro Tachi

Miho Saito

A system for purifying an exhaust gas for use in an automobile is disclosed which does not externally discharge unburnt hydrocarbons until a catalyst becomes active. An adsorbent is provided upstream of the catalyst. A heat exchanger is disposed between an upstream portion of the adsorbent and a portion between the adsorbent and the catalyst for controlling the elevation of the temperature of the adsorbent and for promoting the elevation of the temperature of the catalyst. The unburnt hydrocarbons are absorbed by the adsorbent 4 in the initial period of time from starting of an engine until the catalyst 8 becomes active. Temperature control is made in such a manner that the unburnt hydrocarbons which are adsorbed by the adsorbent 4 begins to be desorbed therefrom substantially simultaneously with the time when the catalyst 8 begins to function. A large quantity of unburnt hydrocarbons which are emitted from an engine immediately after the starting of the engine are prevented from being externally discharged without being treated.

System for purifying exhaust gas for use in an automobile

An apparatus for purifying an exhaust gas emitted from an internal combustion engine, particularly, immediately after starting of the engine, includes a mechanism for reducing the time required to heat a catalyst converter to the activation temperature. The exhaust gas is passed through a preliminary catalyst close to the engine and then through a main catalyst downstream of the catalyst. The engine is operated with an air-fuel mixture which is richer than the amount indicated by the stoichiometric air/fuel ratio for a period of time from when engine is started until the main catalyst is heated to a temperature at which the catalyst can sufficiently perform its purifying capability. The preliminary catalyst is enabled to function at lower temperatures by combusting the exhaust gas which is generated during a rich air-fuel mixture condition. The main catalyst can be heated with the generated combustion heat, resulting in an enhancement in exhaust gas purifying capability.

Apparatus for controlling internal combustion engine

A system for purifying an exhaust gas for use in an automobile is disclosed which does not externally discharge unburnt hydrocarbons until a catalyst becomes active. An adsorbent is provided upstream of the catalyst. A heat exchanger is disposed between an upstream portion of the adsorbent and a portion between the adsorbent and the catalyst for controlling the elevation of the temperature of the adsorbent and for promoting the elevation of the temperature of the catalyst. The unburnt hydrocarbons are absorbed by the adsorbent in the initial period of time from starting of an engine until the catalyst becomes active. Temperature control is made in such a manner that the unburnt hydrocarbons which are adsorbed by the adsorbent begins to be desorbed therefrom substantially simultaneously with the time when the catalyst begins to function. A large quantity of unburnt hydrocarbons which are emitted from an engine immediately after the starting of the engine are prevented from being externally discharged without being treated.

An apparatus is provided for purifying an exhaust gas discharged from an internal combustion engine, which comprises a first exhaust gas passage including a nitrogen oxide removing catalyst and a three way catalyst, a second exhaust gas passage including the three way catalyst, a gas flow regulator for selectively directing the exhaust gas to the first and second exhaust gas passages, and a control unit which directs the exhaust gas to the first exhaust gas passage (thereby passing exhaust gas first through the nitrogen oxide removing catalyst and thereafter through the three way catalyst) when the temperature of the nitrogen oxide removing catalyst is within a hydrocarbon adsorbing range of temperature thereof while the engine is warming up, and to the second exhaust gas passage (thereby passing the exhaust gas only through the three way catalyst) when the temperature of the nitrogen oxide removing catalyst exceeds the hydrocarbon adsorbing range of temperature thereof.

Exhaust gas purifying apparatus and method for internal combustion engine

This invention relates to a method of catalytic combustion using a heat-resistant catalyst and, in particular, relates to a method of catalytic combustion using a heat-resistant catalyst suitable for combustion at a temperature ranging from 800.degree. C. to 1500.degree. C.

Method of catalytic combustion using heat-resistant catalyst

Growing community of inventors

Mito, Japan

Noriko Watanabe