Method of controlling the operation of an aftertreatment system of a motor vehicle

Patent metadata

Field	Value
Publication number	US-10054019-B2
Application number	US-201715413106-A
Country	US
Kind code	B2
Filing date	Jan 23, 2017
Priority date	Jan 22, 2016
Publication date	Aug 21, 2018
Grant date	Aug 21, 2018

Abstract

A method and apparatus are disclosed for controlling the operation of an aftertreatment system for a motor vehicle having a Lean NOx Trap and a tail pipe for conveying exhaust gasses from the LNT to the external environment. Values are calculated for a NOx content in the exhaust gasses flowing in the tail pipe and the quantity of NOx stored in the LNT. A DeNOx request index is calculated as a function of these values. A raw threshold value of the DeNOx request index is calculated as a function of a LNT temperature and of an exhaust gas mass flow. A corrected threshold value of the DeNOx request index is calculated as a function of the raw threshold value of the DeNOx request index and of a correction factor. A DeNOx regeneration is initiated when the calculated value of the DeNOx request index is larger than the corrected threshold value.

First claim

What is claimed is:

1. A method of controlling the operation of an aftertreatment system of a motor vehicle having a Lean NO x Trap (LNT) and a tail pipe for conveying exhaust gasses from the LNT to the external environment comprising:
calculating a value of a first parameter (NOx_TP_Ratio) indicative of a NO x content in the exhaust gasses flowing in the tail pipe;
calculating a value of a second parameter (NOx_Sto_Ratio) indicative of quantity of NO x stored in the LNT;
calculating a value of a DeNO x request index (DeNOx_Req_Ratio) as a function of the calculated value of the first parameter (NOx_TP_Ratio) and of the calculated value of the second parameter (NOx_Sto_Ratio);
calculating a raw threshold value of the DeNO x request index (DeNOx_Ratio_Thr) as a function of a LNT temperature (LNT_Temp) and of an exhaust gas mass flow (Ex_Mass_Flow);
calculating a corrected threshold value of the DeNO x request index (DeNOx_Corr_Thr_Ratio) as a function of the raw threshold value of the DeNO x request index (DeNOx_Req_Ratio) and of a correction factor (DeNOx_Corr), wherein the correction factor (DeNOx_Corr) is calculated as a function of a probability value of a successful completion of a DeNO x regeneration (DeNOx_Succ_Prob); and
initiating a DeNO x regeneration when the calculated value of the DeNO x request index (DeNOx_Req_Ratio) is larger than the corrected threshold value (DeNOx_Corr_Thr_Ratio).

2. The method according to claim 1 , wherein calculating the probability value of a successful completion of a DeNO x regeneration (DeNOx_Succ_Prob) comprises:
calculating a first probability value on the basis of a mission profile (DeNOx_MP_Succ_Prob) of the motor vehicle;
calculating a second probability value on the basis of DeNO x inhibitions (DeNOx_Inh_Succ_Prob); and
calculating the probability value of the successful completion of a DeNO x regeneration (DeNOx_Succ_Prob) as a function of the first and the second probability values.

3. The method according to claim 2 , further comprising calculating the first probability value as a function of the mission profile of the motor vehicle and of a transmission gear.

4. The method according to claim 2 , further comprising determining the mission profile as a function of a speed (VS) of the motor vehicle.

5. The method according to claim 2 , further comprising calculating the second probability value as a function of a DeNOx_inhibition ratio (DeNOx_Inh_Ratio) and of a DeNOx inhibition trigger number (DeNOx_Inh_TN).

6. The method according to claim 5 , wherein calculating the DeNOx inhibition ratio (DeNOx_Inh_Ratio) comprises:
counting, during a predetermined interval of time, an amount of time during which a DeNO x regeneration is inhibited (DeNOx_Inh_Time); and
dividing said amount of time by the predetermined interval of time.

7. The method according to claim 5 , wherein calculating the DeNOx inhibition trigger number (DeNOx_Inh_TN) comprises counting, during a predetermined interval of time, the number of times that a DeNO x regeneration is inhibited.

8. An apparatus for controlling the operation of an aftertreatment system (270) of a motor vehicle having a Lean NO x Trap (LNT) and a tail pipe for conveying exhaust gasses from the LNT to the external environment, the apparatus comprising an electronic control unit, a data carrier having a computer program stored therein, which when executed on the electronic control unit, is configured to:
calculate a value of a first parameter (NOx_TP_Ratio) indicative of a NO x content in the exhaust gasses flowing in the tail pipe;
calculate a value of a second parameter (NOx_Sto_Ratio) indicative of quantity of NO x stored in the LNT;
calculate a value of a DeNO x request index (DeNOx_Req_Ratio) as a function of the calculated value of the first parameter (NOx_TP_Ratio) and of the calculated value of the second parameter (NOx_Sto_Ratio);
calculate a raw threshold value of the DeNO x request index (DeNOx_Ratio_Thr) as a function of a LNT temperature (LNT_Temp) and of an exhaust gas mass flow (Ex_Mass_Flow);
calculate a corrected threshold value of the DeNO x request index (DeNOx_Corr_Thr_Ratio) as a function of the raw threshold value of the DeNO x request index (DeNOx_Req_Ratio) and of a correction factor (DeNOx_Corr), the correction factor (DeNOx_Corr) being calculated as a function of a probability value of a successful completion of a DeNO x regeneration (DeNOx_Succ_Prob); and
initiate a DeNO x regeneration when the calculated value of the DeNO x request index (DeNOx_Req_Ratio) is larger than the corrected threshold value (DeNOx_Corr_Thr_Ratio).

9. A non-transitory computer readable medium comprising a computer program having computer-code stored thereon, which when executed on a processor, is configured to:
calculate a value of a first parameter (NOx_TP_Ratio) indicative of a NO x content in the exhaust gasses flowing in the tail pipe;
calculate a value of a second parameter (NOx_Sto_Ratio) indicative of quantity of NO x stored in the LNT;
calculate a value of a DeNO x request index (DeNOx_Req_Ratio) as a function of the calculated value of the first parameter (NOx_TP_Ratio) and of the calculated value of the second parameter (NOx_Sto_Ratio);
calculate a raw threshold value of the DeNO x request index (DeNOx_Ratio_Thr) as a function of a LNT temperature (LNT_Temp) and of an exhaust gas mass flow (Ex_Mass Flow);
calculate a corrected threshold value of the DeNO x request index (DeNOx_Corr_Thr_Ratio) as a function of the raw threshold value of the DeNO x request index (DeNOx_Req_Ratio) and of a correction factor (DeNOx_Corr), the correction factor (DeNOx_Corr) being calculated as a function of a probability value of a successful completion of a DeNO x regeneration (DeNOx_Succ_Prob); and
initiate a DeNO x regeneration when the calculated value of the DeNO x request index (DeNOx_Req_Ratio) is larger than the corrected threshold value (DeNOx_Corr_Thr_Ratio).

Assignees

• Gm Global Tech Operations Llc

Inventors

• Latrofa Giacomo
• Montinaro Giovanni
• Ramolivo Fabrizio
• Cusanno Luisa
• VENTURINI Matteo
• Maisola Barbara

Classifications

• F01N3/0842 Primary

  Nitrogen oxides · CPC title

• F01N3/0885 Primary

  Regeneration of deteriorated absorbents or adsorbents, e.g. desulfurization of NOx traps · CPC title

• F02D41/0275

  the exhaust gas treating apparatus being a NOx trap or adsorbent · CPC title

• F02D41/0225

  in relation with the gear ratio or shift lever position · CPC title

• F01N13/082

  of tailpipe, e.g. with means for mixing air with exhaust for exhaust cooling, dilution or evacuation (F01N13/20 takes precedence) · CPC title