Method for exhaust gas aftertreatment, and exhaust gas aftertreatment system

Patent metadata

Field	Value
Publication number	US-11377994-B2
Application number	US-202117235749-A
Country	US
Kind code	B2
Filing date	Apr 20, 2021
Priority date	Oct 23, 2018
Publication date	Jul 5, 2022
Grant date	Jul 5, 2022

Abstract

A method for exhaust gas aftertreatment in a gasoline engine and an exhaust gas aftertreatment system are provided. In the method, two catalytic converters arranged in the exhaust gas tract of the gasoline engine are operated in different states. A first three-way catalytic converter is operated in a slightly low-oxygen range, and a second three-way catalytic converter is operated in a slightly oxygen-rich range. Secondary air is furthermore blown into the exhaust gas tract between the two three-way catalytic converters. It is thereby possible to reduce the output of emissions of the gasoline engine to a great extent. An exhaust gas aftertreatment system is likewise explained.

First claim

What is claimed is:

1. A method for exhaust gas aftertreatment in a gasoline engine, the method including:
operating a first three-way catalytic converter arranged in an exhaust gas tract of the gasoline engine in a slightly low-oxygen range;
operating an NOx sensor arranged in the first three-way catalytic converter;
operating a second three-way catalytic converter arranged downstream thereof in the exhaust gas tract of the gasoline engine in a slightly oxygen-rich range; and
blowing secondary air into the exhaust gas tract between the first and second three-way catalytic converters;
wherein the NOx sensor is used as an NH3 sensor in order to implement control of the first three-way catalytic converter in the slightly low-oxygen range (slightly rich range).

2. The method as claimed in claim 1 , wherein a binary lambda probe is used to implement control of the second three-way catalytic converter in the slightly oxygen-rich range (slightly low range).

3. The method as claimed in claim 1 , wherein two-point control of the first three-way catalytic converter is carried out by the NOx sensor.

4. The method as claimed in claim 1 , wherein a linear lambda probe upstream of the first three-way catalytic converter is used.

5. The method as claimed in claim 1 , wherein a secondary air supply is switched on and off alternately for control purposes.

6. An exhaust gas aftertreatment system for a gasoline engine, the exhaust gas aftertreatment system comprising:
an exhaust gas tract;
a first three-way catalytic converter arranged in the exhaust gas tract;
an NOx sensor arranged in the first three-way catalytic converter;
a second three-way catalytic converter arranged downstream thereof in the exhaust gas tract; and
a device for blowing secondary air into the exhaust gas tract between the first and second three-way catalytic converters;
wherein the NOx sensor is used as an NH 3 sensor in order to implement control of the first three-way catalytic converter in the slightly low-oxygen range (slightly rich range).

7. The exhaust gas aftertreatment system as claimed in claim 6 , further comprising a binary lambda probe for control of the second three-way catalytic converter in the slightly oxygen-rich range.

8. The exhaust gas aftertreatment system as claimed in claim 6 , further comprising a linear lambda probe upstream of the first three-way catalytic converter.

9. The exhaust gas aftertreatment system as claimed in claim 6 , wherein the device for blowing in secondary air includes a secondary air pump and a secondary air valve.

10. The exhaust gas aftertreatment system as claimed in claim 6 , wherein the second three-way catalytic converter is designed as an underfloor catalytic converter.

11. The exhaust gas aftertreatment system as claimed in claim 6 , wherein the second three-way catalytic converter is designed as a four-way catalytic converter.

Assignees

• Vitesco Tech Gmbh

Inventors

• Haft Gerhard

Classifications

• F01N13/0093

  the purifying devices are of the same type · CPC title

• F01N3/32

  using air pump (using jet air pumps F01N3/34; pumps in general F04) · CPC title

• F01N3/101 Primary

  Three-way catalysts · CPC title

• F01N3/30

  Arrangements for supply of additional air (control, e.g. using by-passes or variable air pump drives, F01N3/22) · CPC title

• F01N2560/021

  for measuring or detecting ammonia NH3 · CPC title