Method for introducing a reagent medium into an exhaust gas conduit of an internal combustion engine, and apparatus for carrying out the method

• US 8,176,726 B2
• Filed: 04/01/2005
• Issued: 05/15/2012
• Est. Priority Date: 05/05/2004
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Gerlach, Michael
• Primary Examiner(s): Denion, Thomas
• Assistant Examiner(s): BOGUE, JESSE SAMUEL
• Application Number:
  US11/579,513
• Publication Number:
  US 20080264041A1
• Time in Patent Office: 2,601 Days
• Field of Search: 602/77, 602/86, 602/95, 602/74, 602/97, 603/03, 73 157- 172
• US Class Current: 60/277
• CPC Class Codes: B01D 53/90 Injecting reactants
• CPC Class Codes: B01D 53/9431 Processes characterised by a specific device
• CPC Class Codes: B01D 53/9495 Controlling the catalytic process
• CPC Class Codes: F01N 2560/08 the means being a pressure sensor
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 2900/1808 Pressure
• CPC Class Codes: F01N 3/208 Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
• CPC Class Codes: F01N 9/00 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 Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A method for introducing a reagent medium into an exhaust gas conduit of an internal combustion engine, and an apparatus for carrying out the method. Provision is made for a diagnosis of the pressure sensor. In at least one first time interval in which a steady pressure state is expected, a check is made as to whether the pressure signal at least approximately corresponds to the steady-state pressure. In at least one second time interval in which a pressure change occurs, a check is made as to whether the pressure signal at least approximately corresponds to a predetermined test pressure and/or at least approximately exhibits a predetermined change with respect to the steady-state pressure. A fault signal is supplied if at least one of the conditions is not met.

Claims

1. A method for introducing a reagent medium into an exhaust gas conduit of an internal combustion engine, in which at least one pressure sensor is provided, the method comprising:

performing a diagnosis of the pressure sensor, which is at least for detecting the reagent pressure and which provides a pressure signal;

checking, in at least one first time interval, predetermined by a timer, in which an operating pressure is expected, whether a pressure signal at least substantially corresponds to a steady-state pressure;

checking, in at least one second time interval, predetermined by the timer, which is in the period following a controlling, during which the internal combustion engine is already switched off, and in which a pressure decrease is expected, a check is performed as to whether the pressure signal at least one of (a) at least substantially corresponds to a predetermined test pressure and (b) at least substantially exhibits a predetermined change with respect to the operating pressure; and

supplying an error signal if the pressure signal does not correspond to the operating pressure in the first time interval, and if the pressure signal at least one of does not correspond to the predetermined test pressure and does not exhibit the predetermined change in the second time interval.

2. The method according to claim 1, wherein the fault signal is supplied if the pressure signal does not correspond to the operating pressure and if the pressure signal at least one of (a) does not correspond to the predetermined test pressure and (b) does not exhibit the predetermined change.

3. The method according to claim 1, wherein a pressureless state is intended to exist in a first time interval, and a check is made as to whether the pressure signal at least substantially corresponds to an ambient atmospheric pressure.

4. The method according to claim 1, wherein an operating pressure is intended to exist in a first time interval, and a check is made as to whether the pressure signal at least substantially corresponds to the operating pressure.

5. The method according to claim 1, wherein a check is made, at a measurement time located in a second time interval, as to whether the pressure signal at least substantially corresponds to a test pressure.

6. The method according to claim 1, wherein in a second time interval, at least one of a difference quotient and a differential quotient of a time profile of the pressure signal is ascertained and evaluated.

7. The method according to claim 1, wherein the pressure sensor senses at least one of a reagent medium pressure and a compressed air pressure.

8. The method according to claim 1, wherein the reagent medium travels via a pump and a dosing valve into a mixing chamber.

9. The method according to claim 1, wherein ammonia is used to convert nitrogen oxides contained in the exhaust gas into water and nitrogen.

10. The method according to claim 9, wherein the ammonia is obtained in the exhaust gas by hydrolysis.

11. The method according to claim 9, wherein the ammonia can be introduced directly into the exhaust region upstream from a selective catalytic reduction converter.

12. The method according to claim 1, wherein:

the fault signal is supplied if the pressure signal does not correspond to the operating pressure and if the pressure signal at least one of (a) does not correspond to the predetermined test pressure and (b) does not exhibit the predetermined change,

a check is made, at a measurement time located in a second time interval, as to whether the pressure signal at least substantially corresponds to a test pressure,

in a second time interval, at least one of a difference quotient and a differential quotient of a time profile of the pressure signal is ascertained and evaluated, and

the pressure sensor senses at least one of a reagent medium pressure and a compressed air pressure.

13. The method according to claim 12, wherein one of the following is satisfied:

(i) a pressureless state is intended to exist in a first time interval, and a check is made as to whether the pressure signal at least substantially corresponds to an ambient atmospheric pressure; and

(ii) an operating pressure is intended to exist in a first time interval; and

a check is made as to whether the pressure signal at least substantially corresponds to the operating pressure.

14. An apparatus for introducing a reagent medium into an exhaust gas conduit of an internal combustion engine, in which at least one pressure sensor is provided, the apparatus comprising:

a diagnostic arrangement to diagnose the pressure sensor, which is at least for detecting the reagent pressure and which provides a pressure signal;

a first checking arrangement to check, in at least one first time interval, predetermined by a timer, in which an operating pressure is expected, whether a pressure signal at least substantially corresponds to a steady-state pressure;

a second checking arrangement to check, in at least one second time interval, predetermined by the timer, which is in the period following a controlling, during which the internal combustion engine is already switched off, and in which a pressure decrease is expected, a check is performed as to whether the pressure signal at least one of (a) at least substantially corresponds to a predetermined test pressure and (b) at least substantially exhibits a predetermined change with respect to the operating pressure; and

an error arrangement to supply an error signal if the pressure signal does not correspond to the operating pressure in the first time interval, and if the pressure signal at least one of does not correspond to the predetermined test pressure and does not exhibit the predetermined change in the second time interval.

15. The apparatus according to claim 14, wherein the fault signal is supplied if the pressure signal does not correspond to the operating pressure and if the pressure signal at least one of (a) does not correspond to the predetermined test pressure and (b) does not exhibit the predetermined change.

16. The apparatus according to claim 14, wherein a pressureless state is intended to exist in a first time interval, and a check is made as to whether the pressure signal at least substantially corresponds to an ambient atmospheric pressure.

17. The apparatus according to claim 14, wherein an operating pressure is intended to exist in a first time interval, and a check is made as to whether the pressure signal at least substantially corresponds to the operating pressure.

18. The apparatus according to claim 14, wherein a check is made, at a measurement time located in a second time interval, as to whether the pressure signal at least substantially corresponds to a test pressure.

19. The apparatus according to claim 14, wherein in a second time interval, at least one of a difference quotient and a differential quotient of a time profile of the pressure signal is ascertained and evaluated.

20. The apparatus according to claim 14, wherein the pressure sensor senses at least one of a reagent medium pressure and a compressed air pressure.

21. The apparatus according to claim 14, wherein:

the fault signal is supplied if the pressure signal does not correspond to the operating pressure and if the pressure signal at least one of (a) does not correspond to the predetermined test pressure and (b) does not exhibit the predetermined change,

a check is made, at a measurement time located in a second time interval, as to whether the pressure signal at least substantially corresponds to a test pressure,

in a second time interval, at least one of a difference quotient and a differential quotient of a time profile of the pressure signal is ascertained and evaluated, and

the pressure sensor senses at least one of a reagent medium pressure and a compressed air pressure.

22. The apparatus according to claim 21, wherein one of the following is satisfied:

(i) a pressureless state is intended to exist in a first time interval, and a check is made as to whether the pressure signal at least substantially corresponds to an ambient atmospheric pressure; and

(ii) an operating pressure is intended to exist in a first time interval; and

a check is made as to whether the pressure signal at least substantially corresponds to the operating pressure.

23. The apparatus according to claim 22, wherein the reagent medium travels via a pump and a dosing valve into a mixing chamber, and wherein ammonia is used to convert nitrogen oxides contained in the exhaust gas into water and nitrogen.

24. The apparatus according to claim 23, wherein the ammonia is obtained in the exhaust gas by hydrolysis.

25. The apparatus according to claim 23, wherein the ammonia can be introduced directly into the exhaust region upstream from a selective catalytic reduction converter.