Electronic control module for an internal combustion engine

Patent metadata

Field	Value
Publication number	US-9677451-B2
Application number	US-201514792035-A
Country	US
Kind code	B2
Filing date	Jul 6, 2015
Priority date	Jul 5, 2014
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

An electronic control module for operating an internal combustion engine is disclosed. The electronic control module is configured to monitor a first air-fuel equivalence ratio of engine exhaust gases upstream of a NOx trap, and to activate a diagnostic routine for the NOx trap when the first air-fuel equivalence ratio is smaller than one. The diagnostic routine enables the electronic control module to monitor a second air-fuel equivalence ratio of engine exhaust gases downstream of the NOx trap, to use the first and second air-fuel equivalence ratios to calculate an index that is representative of the conversion efficiency of the NOx trap, and to identify a failure of the NOx trap when the efficiency index is lower than a predetermined threshold value.

First claim

What is claimed is:

1. An electronic control module for operating an internal combustion engine, wherein the electronic control module is configured to:
monitor a first air-fuel equivalence ratio of engine exhaust gases upstream of a NOx trap; and
activate a diagnostic routine for the NOx trap when the first air-fuel equivalence ratio is smaller than 1; wherein the diagnostic routine enables the electronic control module to:
monitor a second air-fuel equivalence ratio of engine exhaust gases downstream of the NOx trap; use the first and second air-fuel equivalence ratios to calculate an index that is representative of a conversion efficiency of the NOx trap; and
identify a failure of the NOx trap when the conversion efficiency index is lower than a predetermined threshold value; wherein the electronic control module is configured to:
use the first air-fuel equivalence ratio to calculate a total quantity of hydrocarbons and carbon monoxide entering the NOx trap in a given time period;
use both the first and second air-fuel equivalence ratios to calculate a total quantity of hydrocarbons and carbon monoxide converted in the NOx trap in the same time periods;
calculate the conversion efficiency index as a ratio between the total quantity of hydrocarbons and carbon monoxide converted in the NOx trap and the total quantity of hydrocarbons and carbon monoxide entering the NOx trap; and
wherein the electronic control module is configured to stop calculating total quantities of hydrocarbons and carbon monoxide entering and being converted in the NOx trap when a breakthrough event occurs, wherein the breakthrough event occurs when following conditions are met temporarily: a value of the first air-fuel equivalence ratio is within a prescribed value range; and a value of the second air-fuel equivalence ratio is less than a second threshold value.

2. The electronic control module according to claim 1 , wherein the electronic control module is configured to calculate the total quantity of hydrocarbons and carbon monoxide entering the NOx trap by integrating the following function over time:
f 1= {dot over (m)} b ·(1−AFR up )

wherein:
{dot over (m)} b is a total mass flow rate of the fuel injected into the engine; and
AFR up is the first air-fuel equivalence ratio.

3. The electronic control module according to claim 2 , wherein the electronic control module is configured to calculate the total quantity of hydrocarbons and carbon monoxide converted in der NOx trap by integrating the following function over time:

f
⁢

⁢
2

=

m
.

b

·

(

AFR
dwn

-

AFR
up

AFR
dwn

)

wherein:
{dot over (m)} b is the total mass flow rate of the injected fuel;
AFR up is the first air-fuel equivalence ratio; and
AFR dwn is the second air-fuel equivalence ratio.

4. The electronic control module according to claim 1 , wherein the electronic control module is configured to start the calculations of the total quantities of hydrocarbons and carbon monoxide when the second air-fuel equivalence ratio is less than a predetermined threshold value.

5. The electronic control module according to claim 1 , wherein the electronic control module is configured to cancel the diagnostic routine after completion of the calculations of the total quantities of hydrocarbons and carbon monoxide when the calculated total quantity of hydrocarbons and carbon monoxide entering the NOx trap is smaller than a predetermined threshold value.

6. The electronic control module according to claim 1 , wherein the electronic control module is configured to prevent the start of the calculations of the total quantities of hydrocarbons and carbon monoxide and cancel the diagnostic routine when at least one of the following inhibiting conditions is satisfied: the first air-fuel equivalence ratio becomes greater than one; and the first air-fuel equivalence ratio falls below a predetermined threshold value.

7. The electronic control module according to claim 1 , wherein the electronic control module is configured to cancel the calculations of the total quantities of hydrocarbons and carbon monoxide before they are completed and cancel the diagnostic routine when at least one of the following cancellation conditions is met:
the first air-fuel equivalence ratio becomes greater than one;
the first air-fuel equivalence ratio falls below a predetermined threshold value; and
the second air-fuel equivalence ratio becomes smaller than the first air-fuel equivalence ratio.

8. The electronic control module according to claim 1 wherein the electronic control module is configured to prevent the activation of the diagnostic routine if a request for a DeNOx regeneration operation has not yet been initiated.

9. A method of operating an internal combustion engine comprising:
monitoring a first air-fuel equivalence ratio of engine exhaust gases upstream of a NOx trap; and
activating a diagnostic routine for the NOx trap when the first air-fuel equivalence ratio is smaller than 1; wherein the diagnostic routine includes:
monitoring a second air-fuel equivalence ratio of engine exhaust gases downstream of the NOx trap;
using the first and second air-fuel equivalence ratios to calculate an index that is representative of a conversion efficiency of the NOx trap; and
identifying a failure of the NOx trap when the conversion efficiency index is lower than a predetermined threshold value; and
stopping calculating total quantities of hydrocarbons and carbon monoxide entering and being converted in the NOx trap when a breakthrough event occurs, wherein the breakthrough event occurs when following conditions are met temporarily: a value of the first air-fuel equivalence ratio is within a prescribed value range; and a value of the second air-fuel equivalence ratio is less than a second threshold value.

10. The method according to claim 9 further comprising:
using the first air-fuel equivalence ratio to calculate a total quantity of hydrocarbons and carbon monoxide entering the NOx trap in a given time period;
using both the first and second air-fuel equivalence ratios to calculate a total quantity of hydrocarbons and carbon monoxide converted in the NOx trap in the same time period; and
calculating the efficiency index as a ratio between the total quantity of hydrocarbons and carbon monoxide converted in the NOx trap and the total quantity of hydrocarbons and carbon monoxide entering the NOx.

11. The method according to claim 10 further comprising calculating the total quantity of hydrocarbons and carbon monoxide entering the NOx trap by integrating the following function over time:
f 1= {dot over (m)} b ·(1−AFR up )

wherein:
{dot over (m)} b is a total mass flow rate of the fuel injected into the engine; and

Assignees

• Gm Global Tech Operations Llc

Inventors

• Giordano Alberto
• Argolini Roberto
• Taibi Cristian

Classifications

• F01N2900/1402

  Exhaust gas composition · CPC title

• F01N3/0842

  Nitrogen oxides · CPC title

• F01N2900/0418

  using integration or an accumulated value within an elapsed period · CPC title

• F01N11/007 Primary

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

• F01N2900/1614

  NOx amount trapped in catalyst · CPC title