Exhaust gas purification apparatus of internal combustion engine

Patent metadata

Field	Value
Publication number	US-9605616-B2
Application number	US-201314897917-A
Country	US
Kind code	B2
Filing date	Jul 11, 2013
Priority date	Jul 11, 2013
Publication date	Mar 28, 2017
Grant date	Mar 28, 2017

Abstract

An exhaust gas purification apparatus of an internal combustion engine includes: an NH 3 generating catalyst which generates NH 3 from NOx and H 2 at a rich air-fuel ratio; an in-cylinder injection valve which injects fuel into a cylinder; and a control apparatus which, when setting a rich air-fuel ratio, sets a timing of fuel injection from the in-cylinder injection valve to a second half of a compression stroke when a temperature of the NH 3 generating catalyst is within a first prescribed range and sets a timing f of fuel injection from the in-cylinder injection valve to a first half of an intake stroke when the temperature of the NH 3 generating catalyst is within a second prescribed range that is a higher temperature range than the first prescribed range.

First claim

The invention claimed is:

1. An exhaust gas purification apparatus of an internal combustion engine, comprising:
an NH 3 generating catalyst which is provided in an exhaust passage of the internal combustion engine and which generates NH 3 from NOx and H 2 when an air-fuel ratio of exhaust gas is lower than a stoichiometric air-fuel ratio;
a detector which detects a temperature of the NH 3 generating catalyst;
an in-cylinder injection valve which injects fuel into a cylinder of the internal combustion engine; and
a control apparatus configured to set the air-fuel ratio of exhaust gas lower than the stoichiometric air-fuel ratio to generate NH 3 by the NH 3 generating catalyst, wherein
the control apparatus is configured to, when setting the air-fuel ratio of exhaust gas lower than the stoichiometric air-fuel ratio, set a timing of fuel injection from the in-cylinder injection valve to a second half of a compression stroke in a case where the temperature of the NH 3 generating catalyst as detected by the detector is within a first prescribed range and set a timing of fuel injection from the in-cylinder injection valve to a first half of an intake stroke in a case where the temperature of the NH 3 generating catalyst as detected by the detector is within a second prescribed range that is a higher temperature range than the first prescribed range.

2. The exhaust gas purification apparatus of an internal combustion engine according to claim 1 , further comprising an in-passage injection valve which injects fuel into an intake passage of the internal combustion engine, wherein
the control apparatus is configured to, when setting the air-fuel ratio of exhaust gas lower than the stoichiometric air-fuel ratio, set an amount of fuel injection from the in-passage injection valve to a fuel injection amount necessary for the air-fuel ratio to drop to the stoichiometric air-fuel ratio and set an amount of fuel injection from the in-cylinder injection valve to a fuel injection amount necessary for the air-fuel ratio to drop from the stoichiometric air-fuel ratio to a targeted rich air-fuel ratio.

3. The exhaust gas purification apparatus of an internal combustion engine according to claim 1 , comprising a selective catalytic reduction NOx catalyst, which reduces NOx using NH 3 as a reducing agent, in the exhaust passage on a downstream side of the NH 3 generating catalyst.

4. The exhaust gas purification apparatus of an internal combustion engine according claim 1 , wherein
the control apparatus is configured, when setting the air-fuel ratio of exhaust gas lower than the stoichiometric air-fuel ratio, to:
set the air-fuel ratio of exhaust gas lower than the stoichiometric air-fuel ratio by setting the timing of fuel injection from the in-cylinder injection valve to a second half of a compression stroke in a first prescribed period;
set air-fuel ratio of exhaust gas lower than the stoichiometric air-fuel ratio by setting the timing of fuel injection from the in-cylinder injection valve to a second half of a compression stroke in a second prescribed period that is a period subsequent to the first prescribed period and, at the same time, when the temperature of the NH 3 generating catalyst as detected by the detector is within a first prescribed range; and
set air-fuel ratio of exhaust gas lower than the stoichiometric air-fuel ratio by setting the timing of fuel injection from the in-cylinder injection valve to a first half of an intake stroke in the second prescribed period and, at the same time, when the temperature of the NH 3 generating catalyst as detected by the detector is within a second prescribed range that is a higher temperature range than the first prescribed range.

5. The exhaust gas purification apparatus of an internal combustion engine according to claim 4 , wherein an air-fuel ratio of exhaust gas in the first prescribed period is lower than an air-fuel ratio of exhaust gas in the second prescribed period.

6. The exhaust gas purification apparatus of an internal combustion engine according to claim 4 , further comprising:
a catalyst which is provided in the exhaust passage on an upstream side of the NH 3 generating catalyst and which has oxygen storage capability, and a gas sensor which is provided in the exhaust passage on a downstream side of the catalyst with oxygen storage capability and an upstream side of the NH 3 generating catalyst and which detects an air-fuel ratio of exhaust gas, wherein
the first prescribed period is at least a period from when an air-fuel ratio of exhaust gas on an upstream side of the catalyst with oxygen storage capability drops to below the stoichiometric air-fuel ratio to when the air-fuel ratio of exhaust gas as detected by the gas sensor drops to a rich air-fuel ratio that is lower than the stoichiometric air-fuel ratio.

Assignees

• Suzuki Kotaro
• Toyota Motor Co Ltd

Inventors

• Suzuki Kotaro

Classifications

• Y02T10/44

  Cross-Sectional Technologies · mapped topic

• F01N3/2073 Primary

  Means for generating a reducing substance from the exhaust gases · CPC title

• F01N2610/02

  the substance being ammonia or urea · CPC title

• Y02T10/47

  Cross-Sectional Technologies · mapped topic

• F02D41/401

  Controlling injection timing (F02D41/402 takes precedence) · CPC title