Exhaust gas purification apparatus

Patent metadata

Field	Value
Publication number	US-9388757-B2
Application number	US-201214367244-A
Country	US
Kind code	B2
Filing date	Dec 21, 2012
Priority date	Dec 22, 2011
Publication date	Jul 12, 2016
Grant date	Jul 12, 2016

Abstract

The exhaust gas purification apparatus 100 according to the present invention is provided with an exhaust gas purification catalyst 40 , an upstream O 2 sensor 14 , a downstream O 2 sensor 15 , and a control section 30 that executes main F/B control and sub-F/B control. This exhaust gas purification apparatus 100 contains, on a support in a prescribed region 45 from a catalyst-outlet-side end 43 a at the downstream side of an exhaust gas purification catalyst 40 , an OSC material having a pyrochlore structure and an OSC material having an oxygen storage rate that is faster than that of the OSC material having a pyrochlore structure.

First claim

The invention claimed is:

1. An exhaust gas purification apparatus that is disposed in an exhaust system of an internal combustion engine and that purifies an exhaust gas, the exhaust gas purification apparatus comprising:
an exhaust gas purification catalyst that is disposed in the exhaust system and that has a catalyst layer formed on a substrate and including a support containing an OSC material having an oxygen storage capacity and a precious metal catalyst supported on this support;
an upstream O 2 sensor that is disposed in the exhaust system upstream from the exhaust gas purification catalyst and that detects an upstream O 2 concentration, which is an oxygen concentration in the exhaust gas on the upstream side of the exhaust gas purification catalyst;
a downstream O 2 sensor that is disposed in the exhaust system downstream from the exhaust gas purification catalyst and that detects a downstream O 2 concentration, which is an oxygen concentration in the exhaust gas on the downstream side of the exhaust gas purification catalyst; and
a control section that is configured to be capable of executing main feedback control that calculates an air/fuel ratio for an air-fuel mixture being supplied to the internal combustion engine based on the upstream O 2 concentration and that sets a first control target value based on the calculated air/fuel ratio and a predetermined target air/fuel ratio, sub-feedback control that sets a second control target value by correcting the first control target value based on the downstream O 2 concentration, and air/fuel ratio adjustment control that adjusts the air/fuel ratio of the air-fuel mixture supplied to the internal combustion engine based on the second control target value,
wherein the support in a prescribed region from a catalyst-outlet-side end at the downstream side of the exhaust gas purification catalyst contains the OSC material, wherein the OSC material comprises a first OSC material having a pyrochlore structure and a second OSC material having an oxygen storage rate that is faster than that of the first OSC material having a pyrochlore structure,
wherein the second OSC material has a fluorite structure.

2. The exhaust gas purification apparatus according to claim 1 , wherein a length, in the exhaust gas flow direction, of the prescribed region from the catalyst-outlet-side end is from 10% to 50% of a total length of the catalyst layer of the exhaust gas purification catalyst.

3. The exhaust gas purification apparatus according to claim 1 , wherein the downstream O 2 sensor is a ceramic oxygen sensor in which an intermediate layer formed of an oxide conductor is sandwiched between a measurement electrode and a reference electrode and in which a porous coating layer made of a metal oxide is formed on the measurement electrode.

4. The exhaust gas purification apparatus according to claim 1 , wherein a specific surface area based on the BET method of the OSC material having a pyrochlore structure is not more than 10 m 2 /g.

5. The exhaust gas purification apparatus according to claim 1 , wherein both the OSC material having a pyrochlore structure and the OSC material having a faster oxygen storage rate than the OSC material having a pyrochlore structure are a ceria-zirconia complex oxide.

6. The exhaust gas purification apparatus according to claim 1 , wherein in the sub-feedback control, the control section sets the second control target value by adjusting the target air/fuel ratio based on the downstream O 2 concentration and correcting the first control target value by comparing this post-adjustment target air/fuel ratio with the first control target value.

Assignees

• Toyota Motor Co Ltd

Inventors

• Onoe Ryota
• Kuno Oji
• Aoki Yuki
• Kabashima Nobusuke

Classifications

• B01J35/735

  Pyrochlore-type A2B2O7 · CPC title

• B01J2235/15

  X-ray diffraction · CPC title

• B01J35/30

  characterised by their physical properties · CPC title

• B01J23/63 Primary

  with rare earths or actinides · CPC title

• Y02T10/22

  Cross-Sectional Technologies · mapped topic