Exhaust gas purifying apparatus

Abstract

A throttle unit placed in an exhaust gas passage controls an opening-ratio of each of first and second valve members to control a gas-flow sectional area of the exhaust gas passage. When the temperature of a three-way catalyst is low, the throttle unit introduces the exhaust gas flow into a part of an outer-periphery of the three-way catalyst. This control can rapidly increase the temperature of the three-way catalyst from an early period of starting an internal combustion engine within a short period of time. The throttle unit increases the gas-flow sectional area of the exhaust gas passage according to increasing the temperature of the three-way catalyst. When the three-way catalyst reaches its activation temperature, the throttle unit instructs the first and second valve members to fully open. This decreases a pressure loss of the exhaust gas because the exhaust gas is supplied into the entire of the three-way catalyst.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is related to and claims priority from Japanese Patent Application No. 2008-8305 filed on Jan. 17, 2008, the contents of which are hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to an exhaust gas purifying apparatus using a catalyst such as a three way catalyst capable of purifying an exhaust gas emitted from an internal combustion engine such as a diesel engine under a low temperature of the catalyst in the early period of starting the internal combustion engine.[0004]2. Description of the Related Art[0005]Internal combustion engines such as diesel engines and gasoline engines include a problem of increasing the amount of specified materials such as hydro carbon (HC), carbon monoxide (CO), and nitrogen oxide (NOx) contained in an exhaust gas emitted from such an internal combustion engine mounted to a vehicle when the temperature of catalyst p...

AI Technical Summary

Benefits of technology

[0010]When observed from the flowing direction of the exhaust gas in the exhaust gas passage formed in the exhaust gas pipe, the throttle unit is placed on at least one of the upstream side and the downstream side thereof. The throttle unit locally introduces the exhaust gas into a part of the catalyst placed in the catalyst unit when the temperature of the catalyst is lower than its activation temperature. That structure allows the exhaust gas emitted from an internal combustion engine to be introduced into the part of the catalyst when the temperature of the catalyst is low, namely, in the early period of starting the internal combustion engine. This allows the temperature of the part of the catalyst to locally and rapidly rise, through which the exhaust gas is concentrated in flow to the part of the catalyst such as the central part or the outer peripheral part of the catalyst. On th

Problems solved by technology

Internal combustion engines such as diesel engines and gasoline engines include a problem of increasing the amount of specified materials such as hydro carbon (HC), carbon monoxide (CO), and nitrogen oxide (NOx) contained in an exhaust gas emitted from such an internal combustion engine mounted to a vehicle when the temperature of catalyst placed in an exhaust gas purifying apparatus mounted to the vehicle is low, for example, during early period of starting the internal combustion engine.

For this reason, the catalyst placed in the exhaust gas purifying apparatus does not adequately re

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