Method for operating an exhaust gas aftertreatment, device for controlling an exhaust gas after treatment, exhaust gas aftertreatment and internal combustion engine having exhaust gas after treatment

Patent metadata

Field	Value
Publication number	US-2016131012-A1
Application number	US-201414897051-A
Country	US
Kind code	A1
Filing date	Jun 3, 2014
Priority date	Jun 11, 2013
Publication date	May 12, 2016
Grant date	—

Abstract

A method and a device for operating an exhaust gas aftertreatment, wherein a diesel particulate filter is regenerated during the operation, in particular passively regenerated, wherein a corrected differential pressure is calculated from a current differential pressure across the diesel particulate filter at a current exhaust gas volumetric flow rate and with a current correction factor. The current correction factor is determined by determining a lower differential pressure in a predetermined time interval at a defined exhaust gas volumetric flow rate, in particular in a specified exhaust gas volumetric flow rate interval around the defined exhaust gas volumetric flow rate, and comparing the lower differential pressure with a specified current reference value and, depending thereon, calculating a new correction factor or retaining the previous correction factor as the current correction factor.

First claim

1 - 15 . (canceled)

16 . A method for operating an exhaust gas aftertreatment in which a diesel particulate filter is regenerated during operation, comprising the steps of:
measuring a current differential pressure across the diesel particulate filter at a current exhaust gas volumetric flow rate and determining a current correction factor for a differential pressure; and calculating a corrected differential pressure based on the current differential pressure and the current correction factor; wherein the current correction factor is determined at least by the steps of: determining a lower differential pressure in a predetermined time interval at a defined exhaust gas volumetric flow rate; and comparing the lower differential pressure with a specified current reference value, and as a function of that comparison, calculating a new correction factor or retaining the previous correction factor as the current correction factor.

17 . The method according to claim 16 , wherein the time interval is a specified exhaust gas volumetric flow rate interval around the defined exhaust gas volumetric flow rate.

18 . The method according to claim 16 , wherein
when the lower differential pressure is above the specified current reference value a new correction factor is calculated based on the previous correction factor, wherein the new correction factor is assigned to the current correction factor for correspondence; and when the lower differential pressure is below the specified current reference value the previous correction factor is retained, wherein the current correction factor corresponds to the previous correction factor.

19 . The method according to claim 16 , wherein the current differential pressure is filtered and/or subjected to a plausibility check and a filtered and/or plausibility-checked value of the current differential pressure is used to determine the correction factor.

20 . The method according to claim 19 , wherein the filtered and/or plausibility-checked valve of the current differential pressure is used to determine the corrected differential pressure.

21 . The method according to claim 16 , wherein the lower differential pressure is sent to a confidence check to produce a trustworthy value of the lower differential pressure that is used for the comparison.

22 . The method according to claim 21 , wherein the lower differential pressure has the trustworthy value if the lower differential pressure is acquired at values of a current exhaust gas volumetric flow rate which are constant as a function of time for a predetermined first confidence period, which values correspond to a value of the defined exhaust gas volumetric flow rate; and/or
the lower differential pressure remains essentially unchanged as a function of time for a predetermined second confidence period.

23 . The method according to claim 22 , wherein the values correspond to values of the current exhaust gas volumetric flow rate which lie in a specified exhaust gas volumetric flow rate interval around the value of the defined exhaust gas volumetric flow rate.

24 . The method according to claim 21 , wherein the lower differential pressure is a time-wise local minimum and/or a time-wise absolute minimum differential pressure.

25 . The method according to claim 16 , wherein the specified current reference value is a reference differential pressure value of the diesel particulate filter in a new state or in a preferred load state of the diesel particulate filter.

26 . The method according to claim 16 , wherein the calculation of the corrected differential pressure based on the current differential pressure and the current correction factor comprises the steps of:
calculating a current correction value as a product of the current correction factor times a current exhaust gas volumetric flow rate; and calculating the corrected differential pressure by subtracting the current correction value from the current differential pressure.

27 . The method according to claim 16 , wherein, if the lower differential pressure is above the specified current reference value, the new correction factor is calculated by adding a defined constant to the previous correction factor.

28 . The method according to claim 16 , wherein, if the lower differential pressure is above the specified current reference value, a new reference value is calculated that is obtained by adding the current reference value to a product of the current correction factor times the defined exhaust gas volumetric flow rate.

29 . The method according to claim 16 , wherein the current differential pressure is measured regularly; values of the current differential pressure for determining the lower differential pressure are plotted regularly and the lower differential pressure is determined based on plotted values of the current differential pressure in a predetermined time interval at a defined exhaust gas volumetric flow rate.

30 . The method according to claim 29 , wherein the current differential pressure is measured continuously and the values of the current differential are plotted continuously.

31 . The method according to claim 16 , further comprising a control step, in which the corrected differential pressure is compared with a predetermined threshold value, and a regeneration of the diesel particulate filter is initiated when the threshold value is exceeded.

32 . The method according to claim 31 , wherein the regeneration includes a thermomanagement.

33 . A device for controlling an exhaust gas aftertreatment system with a diesel particulate filter, wherein the device is configured to carry out a method according to claim 16 .

34 . An exhaust gas aftertreatment system comprising: a diesel particulate filter; and a device according to claim 33 .

35 . An internal combustion engine comprising: an engine; and an exhaust gas aftertreatment system according to claim 34 .

Assignees

• Mtu Friedrichshafen Gmbh

Inventors

• Prospero Andrea
• Späder Tim
• Merk Stefan

Classifications

• Y02T10/40

  Engine management systems · CPC title

• F01N11/00

  Monitoring or diagnostic devices for exhaust-gas treatment apparatus · CPC title

• F01N2550/04

  Filtering activity of particulate filters · CPC title

• F01N2900/1411

  Exhaust gas flow rate, e.g. mass flow rate or volumetric flow rate · CPC title

• F01N2900/1611

  Particle filter ash amount · CPC title