Exhaust emission control apparatus for internal combustion engine
AssigneeToyota Jidosha Kabushiki Kaisha
InventorsKohei Yoshida, Shinichi Takeshima
Life of this patent
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Abstract
In an exhaust emission control apparatus having an NOx catalyst disposed on an exhaust passage of an internal combustion engine, the present invention is intended to suppress deterioration in exhaust emissions when the temperature of the NOx catalyst is raised. In case where the temperature of the NOx catalyst need be raised, an amount of nitrogen oxides occluded in the NOx catalyst is decreased in advance to the raising of the temperature of the NOx catalyst, whereby the amount of nitrogen oxides to be discharged from the NOx catalyst upon raising the temperature of the NOx catalyst can be decreased.
Claims17
An exhaust emission control apparatus for an internal combustion engine, comprising:
- an NOx catalyst disposed in an exhaust passage of said internal combustion engine;
- a temperature raising section for raising the temperature of said NOx catalyst;
- a nitrogen oxides reducing section for reducing an amount of nitrogen oxides occluded in said NOx catalyst, before said temperature raising section is operated to raise the temperature of said NOx catalyst, more than when the temperature of the NOx catalyst is not raised;
- and
- a particulate filter for collecting particulate matter in an exhaust,
- wherein said temperature raising section raises the temperature of said NOx catalyst when said particulate matter collected by said particulate filter is removed.
An exhaust emission control apparatus for an internal combustion engine comprising:
- an NOx catalyst disposed in an exhaust passage of said internal combustion engine;
- a temperature raising section for raising the temperature of said NOx catalyst;
- a first reducing agent supplying section for supplying a reducing agent to said NOx catalyst when an amount of nitrogen oxides occluded in said NOx catalyst becomes more than or equal to a predetermined amount;
- a second reducing agent supplying section for supplying an amount of said reducing agent more than that supplied by said first reducing agent supplying section to said NOx catalyst before said temperature raising section is operated to raise the temperature of said NOx catalyst;
- and
- a particulate filter for collecting particulate matter in an exhaust,
- wherein said temperature raising section raises the temperature of said NOx catalyst when said particulate matter collected by said particulate filter is removed.
An exhaust emission control apparatus for an internal combustion engine comprising:
- an NOx catalyst disposed in an exhaust passage of said internal combustion engine;
- a temperature raising section for raising the temperature of said NOx catalyst;
- an estimating section for estimating an amount of nitrogen oxides occluded in said NOx catalyst;
- an operation control section adapted to permit an operation of said temperature raising section when the amount of nitrogen oxides estimated by said estimating section is less than a predetermined amount;
- and
- a particulate filter for collecting particulate matter in an exhaust,
- wherein said temperature raising section raises the temperature of said NOx catalyst when said particulate matter collected by said particulate filter is removed.
An exhaust emission control method for an internal combustion engine, comprising:
- a particulate matter removing step for removed particulate matter in an exhaust collected by a particulate filter;
- a temperature raising step for raising the temperature of an NOx catalyst disposed in an exhaust passage of said internal combustion engine when said particulate matter collected by said particulate filter is removed;
- and
- an nitrogen oxides reducing step for reducing an amount of nitrogen oxides occluded in said NOx catalyst before said temperature raising step by an amount more than when the temperature of the NOx catalyst is not raised.
An exhaust emission control method for an internal combustion engine, comprising:
- a particulate matter removing step for removing particulate matter in an exhaust collected by a particulate filter;
- a temperature raising step for raising the temperature of an NOx catalyst disposed in an exhaust passage of said internal combustion engine when said particular matter collected by said particulate filter is removed;
- and
- a nitrogen oxides reducing step for reducing an amount of nitrogen oxides occluded in said NOx catalyst by supplying a reducing agent to said NOx catalyst when the amount of nitrogen oxides occluded in said NOx catalyst becomes more than or equal to a predetermined amount,
- wherein an amount of reducing agent supplied to said NOx catalyst is increased in said nitrogen oxides reducing step before said temperature raising step.
An exhaust emission control method for an internal combustion engine comprising:
- a particulate matter removing step for reducing particulate matter in an exhaust collected by a particulate filter;
- an estimating step for estimating an amount of nitrogen oxides occluded in an NOx catalyst disposed in an exhaust passage of said internal combustion engine;
- and
- a temperature raising step for raising the temperature of said NOx catalyst on the condition that the amount of nitrogen oxides estimated in said estimating step is less than a predetermined amount, when said particulate matter collected by said particulate filter is removed.
Dependencies are inferred from the claim text.