Method and device for diagnosing a differential pressure sensor of a particle filter

Patent metadata

Field	Value
Publication number	US-10774723-B2
Application number	US-201816020539-A
Country	US
Kind code	B2
Filing date	Jun 27, 2018
Priority date	Jul 6, 2017
Publication date	Sep 15, 2020
Grant date	Sep 15, 2020

Abstract

In a method and a device for diagnosing a differential pressure sensor of a particle filter of an internal combustion engine, where the differential pressure sensor is connected via a first pressure line to an exhaust-gas system upstream from the particle filter and via a second pressure line to the exhaust-gas system downstream from the particle filter and upstream from a rear muffler, a diagnosis of the first or second pressure lines is performed by evaluating a comparison of a differential pressure signal from a differential pressure sensor with modeled pressure values.

First claim

What is claimed is:

1. A method for diagnosing connections, to an exhaust-gas system, of a differential-pressure sensor of a particle filter of an internal combustion system, the differential-pressure sensor being connected (a) via a first pressure line to the exhaust-gas system upstream from the particle filter, and (b) via a second pressure line to the exhaust-gas system downstream from the particle filter and upstream from at least one rear muffler, comprising the following steps:
ascertaining a measured pressure drop over the particle filter from a differential pressure signal from the differential-pressure sensor;
forming a first cross-correlation of the measured pressure drop and a modeled pressure drop over the particle filter, the modeled pressure drop over the particle filter being ascertained using a first stored characteristics map;
comparing the first cross-correlation to a modeled pressure drop over the rear muffler, the modeled pressure drop over the rear muffler being ascertained using a second stored characteristics map; and
determining a fault of the first or second pressure line based on the comparing.

2. The method of claim 1 , further comprising the following step:
forming a second cross-correlation of the measured pressure drop, the modeled pressure drop over the particle filter, and the modeled pressure drop over the rear muffler;
wherein the comparison includes comparing the second cross-correlation to the first cross-correlation, and wherein the determining of the fault of the first or second pressure line includes determining a fault of the second pressure line in response to a standard deviation of the first cross-correlation exceeding a standard deviation of the second cross-correlation.

3. The method of claim 2 , wherein the determining of the fault of the first or second pressure line includes evaluating a magnitude of the first and second cross-correlations, evaluating an abrupt change in the magnitude of the first and the second cross-correlations in a direction of an increase, and determining, based on the abrupt change, the fault of the second pressure line.

4. The method of claim 1 , further comprising the following step:
forming a second cross-correlation of the measured pressure drop over the particle filter and the modeled pressure drop over the rear muffler;
wherein the comparison includes comparing the second cross-correlation to the first cross-correlation, and wherein the determining of the fault of the first or second pressure line includes determining a fault of the first pressure line responsive to a standard deviation of the first cross-correlation exceeding a standard deviation of the second cross-correlation.

5. The method of claim 4 , wherein the determining of the fault of the first or second pressure line includes evaluating an algebraic sign of the first or second cross-correlations, and determining the fault of the first pressure line responsive to a change in the evaluated algebraic sign.

6. A device for diagnosing connections, to an exhaust-gas system, of a differential pressure sensor of a particle filter of an internal combustion engine, the differential pressure sensor being connected (a) via a first pressure line to the exhaust-gas system upstream from the particle filter, and (b) via a second pressure line to an exhaust-gas system downstream from the particle filter and upstream from a rear muffler, the device comprising:
a processor, wherein the processor is configured to:
obtain a differential pressure signal from a pressure sensor;
ascertain a measured pressure drop over the particle filter from the obtained differential pressure signal;
form a first cross-correlation of the measured pressure drop and a modeled pressure drop over the particle filter, the modeled pressure drop over the particle filter being ascertained using a first stored characteristics map;
compare the first correlation to a modeled pressure drop over the rear muffler, the modeled pressure drop over the rear muffler being ascertained using a second stored characteristics map; and
determine a fault of the first or second pressure line based on the comparing.

7. The device of claim 6 , wherein the processor is further configured to:
form a second cross-correlation of the measured pressure drop, the modeled pressure drop over the particle filter, and the modeled pressure drop over the rear muffler;
wherein the comparison includes comparing the second cross-correlation to the first cross-correlation, and wherein the determination of the fault of the first or second pressure line includes determining a fault of the second pressure line in response to a standard deviation of the first cross-correlation exceeding a standard deviation of the second cross-correlation.

8. The device of claim 7 , wherein the determination of the fault of the first or second pressure line includes the processor evaluating a magnitude of the first and second cross-correlations, evaluating an abrupt change in the magnitude of the first and the second cross-correlations in a direction of an increase, and determining, based on the abrupt change, the fault of the second pressure line.

9. The device of claim 6 , wherein the processor is further configured to:
form a second cross-correlation of the measured pressure drop over the particle filter and the modeled pressure drop over the rear muffler;
wherein the comparison includes the processor comparing the second cross-correlation to the first cross-correlation, and wherein the determination of the fault of the first or second pressure line includes determining a fault of the first pressure line responsive to a standard deviation of the first cross-correlation exceeding a standard deviation of the second cross-correlation.

10. The device of claim 9 , wherein the determination of the fault of the first or second pressure line includes the processor evaluating an algebraic sign of the first or second cross-correlations, and determining the fault of the first pressure line responsive to a change in the evaluated algebraic sign.

Assignees

• Bosch Gmbh Robert

Inventors

• Stephani Martin
• Brandt Martin
• Lian Yunjie

Classifications

• Y02T10/40

  Engine management systems · CPC title

• F01N2560/08

  the means being a pressure sensor · CPC title

• F01N2550/04

  Filtering activity of particulate filters · CPC title

• F01N2900/0418

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

• F01N11/00 Primary

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