Aftertreatment system for internal combustion engines

Patent metadata

Field	Value
Publication number	US-9551249-B2
Application number	US-201514614055-A
Country	US
Kind code	B2
Filing date	Feb 4, 2015
Priority date	Feb 5, 2014
Publication date	Jan 24, 2017
Grant date	Jan 24, 2017

Abstract

An aftertreatment system of an internal combustion engine is disclosed. The aftertreatment system includes in a sequence along the exhaust pipe, a lean NOx trap and a particulate filter. An air/fuel ratio sensor is located upstream of the lean NOx trap and downstream of the turbine outlet to determine the air/fuel ratio during a regeneration process (DeNOx) in the lean NOx trap. A NOx sensor is located downstream of the lean NOx trap or downstream of the particulate filter, to determine NOx in the exhaust pipe. A turbine temperature is determined in accordance with a first means, and a temperature during a desulphation process (DeSOx) in the lean NOx trap is determined in accordance with a second means. At least one of the first and second means for determining a temperature may be a temperature sensor.

First claim

What is claimed:

1. An aftertreatment system for an internal combustion engine having a turbine and an exhaust pipe connected to a turbine outlet, the aftertreatment system comprising:
a lean NOx trap and a particulate filter in a sequence along the exhaust pipe;
an air/fuel ratio sensor located upstream of the lean NOx trap and downstream of the turbine outlet, the air/fuel ratio sensor configured to determine an air/fuel ratio during a NOx regeneration process in the lean NOx trap;
a NOx sensor located downstream of at least one of the lean NOx trap and the particulate filter, the NOx sensor configured to determine a NOx tailpipe emission in the exhaust pipe;
a first thermal detector configured to determine an inlet temperature upstream of the turbine;
a second thermal detector configured to determine an LNT temperature during a desulphation process in the lean NOx trap; and
a controller in communication with the air/fuel ratio sensor, the NOx sensor and the first and second thermal detectors, wherein the controller is configured:
initiate the NOx regeneration process when: (i) the NOx tailpipe emission provided from the NOx sensor exceeds a NOx amount threshold, (ii) the inlet temperature provided from the first thermal detector is above a first temperature threshold, and (iii) the LNT temperature provided from the second thermal detector is above a second temperature threshold; and
control the NOx regeneration process usin the air/fuel ratio provided from the air/fuel ratio sensor and the NOx tailpipe emission from the NOx sensor such that the air/fuel ratio remains below an airlfuel rutratio threshold during the NOx regeneration process.

2. The aftertreatment system according to claim 1 further comprising a third thermal detector configured to determine a temperature at the lean NOx trap inlet.

3. The aftertreatment system according to claim 1 , wherein said lean NOx trap and said particulate filter are configured to be close coupled to the turbine outlet.

4. The aftertreatment system according to claim 3 further comprising a third thermal detector configured to determine a temperature at the lean NOx trap inlet.

5. An internal combustion engine comprising a turbine and an exhaust pipe connected to a turbine outlet and an aftertreatment system according to claim 1 .

6. A method of operating a lean NOx trap of an aftertreatment system, wherein the method comprises:
evaluating a NOx storage amount in a lean NOx trap as a function of a NOx amount, which derives from an engine combustion, and a NOx measurement downstream of the lean NOx trap, which is performed by a NOx sensor;
evaluating NOx tailpipe emissions as a function of the NOx storage amount;
initiating a NOx regeneration process when: (i) a NOx tailpipe emissions provided from the NOx sensor exceed a NOx amount threshold, (ii) a temperature value provided by a temperature sensor upstream of a turbine is above a first temperature threshold, and (iii) a temperature value provided by a temperature sensor downstream of the lean NOx trap is above a second temperature threshold; and
controlling the NOx regeneration process by using the air/fuel ratio values provided by an air/fuel ratio sensor located upstream of the lean NOx trap and the NOx measurement provided by the NOx sensor such that the air/fuel ratio value remains below an air/fuel ratio threshold during the NOx regeneration process.

7. A non-transitory computer readable medium comprising a computer-code executable on a processor such that the processor is configured to:
evaluate a NOx storage amount in a lean NOx trap as a function of a NOx amount, which derives from an engine combustion, and a NOx measurement downstream of the lean NOx trap, which is performed by a NOx sensor;
evaluate NOx tailpipe emissions as a function of the NOx storage amount;
initiating a NOx regeneration process when: (i) a NOx tailpipe emissions provided from the NOx sensor exceed a NOx amount threshold, (ii) a temperature value provided by a temperature sensor upstream of a turbine is above a first temperature threshold, and (iii) a temperature value provided by a temperature sensor downstream of the lean NOx trap is above a second temperature threshold; and
control the NOx regeneration process by using the air/fuel ratio values provided by an air/fuel ratio sensor located upstream of the lean NOx trap and the NOx measurement provided by the NOx sensor such that the air/fuel ratio value remains below an air/fuel ratio threshold during the NOx regeneration process.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Argolini Roberto
• Mercuri Davide

Classifications

• F01N3/0814

  combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts · CPC title

• F01N11/007

  the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus · CPC title

• F01N3/021

  by means of filters · CPC title

• F01N9/00 Primary

  Electrical control of exhaust gas treating apparatus (monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00) · CPC title

• F02B37/00

  Engines characterised by provision of pumps driven at least for part of the time by exhaust · CPC title