Method for monitoring a subsystem installed in a motor vehicle

• US 9,513,191 B2
• Filed: 12/10/2011
• Issued: 12/06/2016
• Est. Priority Date: 06/09/2011
• Status: Active Grant

• Current Assignee: Daimler AG (Mercedes-Benz Group AG)
• Original Assignee: Daimler AG (Mercedes-Benz Group AG)
• Inventors: Schankula, Herbert, Richter, Markus
• Primary Examiner(s): Dager, Jonathan M
• Application Number:
  US14/124,062
• Publication Number:
  US 20140277904A1
• Time in Patent Office: 1,823 Days
• Field of Search: 701 29-500
• US Class Current: 1/1
• CPC Class Codes: F01N 11/00 Monitoring or diagnostic devices for exhaust-gas treatment apparatus , e.g. for catalytic activity safety, indicating or supervising devices for internal combustion engines F02B77/08; testing of machines G01M13/00
• CPC Class Codes: F01N 2550/02 Catalytic activity of catalytic converters
• CPC Class Codes: F01N 2550/03 of sorbing activity of adsorbents or absorbents
• CPC Class Codes: F01N 2900/0421 using an increment counter when a predetermined event occurs
• CPC Class Codes: F01N 2900/10 said parameters being related to the vehicle or its components
• CPC Class Codes: F01N 2900/102 Travelling distance
• CPC Class Codes: F01N 2900/12 said parameters being related to the vehicle exterior
• CPC Class Codes: F01N 3/2066 Selective catalytic reduction [SCR]
• CPC Class Codes: F02D 2400/11 After-sales modification devices designed to be used to modify an engine afterwards
• CPC Class Codes: F02D 41/0235 in relation with the state of the exhaust gas treating apparatus control of exhaust gas treating apparatus per se F01N
• CPC Class Codes: F02D 41/22 Safety or indicating devices for abnormal conditions in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809
• CPC Class Codes: G01M 15/05 by combined monitoring of two or more different engine parameters
• CPC Class Codes: G01M 15/10 by monitoring exhaust gases or combustion flame
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A method for monitoring a subsystem installed in a motor vehicle involves a diagnostic unit checking the subsystem for system errors at least during driving cycles of the motor vehicle, the check being carried out for an occurrence as well as for a correction of a system error. The diagnostic unit carries out a misuse assessment based on a frequency of detection of the occurrence and/or the correction of the system error in order to determine whether the detected occurrence and/or the detected correction of the system error is/are based on misuse. If occurrence of the system error is detected, a restricted operating mode is activated or an activated restricted operating mode is continued in which drivability of the vehicle is restricted after a predefinable number of driving cycles has elapsed or after a predefinable travel distance has passed without the correction of the system error being detected.

Claims

1. A method for monitoring a subsystem installed in a motor vehicle, the method comprising:

checking, by a diagnostic unit, the subsystem for system errors at least during driving cycles of the motor vehicle, wherein the check is performed for an occurrence of a system error and a correction of the system error;

performing, by the diagnostic unit, a misuse assessment based on a frequency of detection of the occurrence and the correction of the system error in order to determine whether the detected occurrence and the detected correction of the system error is based on misuse, wherein misuse is the occurrence of the system error or the correction of the system error due to an intervention in the subsystem impermissibly carried out by a user of the motor vehicle,

activating a restricted driving mode or continuing an activated restricted driving mode if occurrence of the system error is detected, wherein in the restricted driving mode drivability of the vehicle is restricted after

a predefined number of driving cycles has elapsed without the correction of the system error being detected, or

a predefined travel distance has passed without the correction of the system error being detected.

2. The method according to claim 1, wherein the monitored subsystem is an exhaust aftertreatment system associated with an internal combustion engine of the motor vehicle.

3. The method according to claim 1, wherein the monitored subsystem is a selective catalytic reduction (SCR) exhaust aftertreatment system for reducing nitrogen oxides contained in the exhaust gas of the internal combustion engine, and the diagnostic unit checks the SCR exhaust aftertreatment system for consumption-relevant system errors, which in comparison to an error-free SCR exhaust aftertreatment system result in a significantly decreased consumption of an SCR reducing agent provided for nitrogen oxides reduction.

4. The method according to claim 1, wherein a memory is provided for the diagnostic unit which has memory locations for at least status information determined in the driving cycles, the status information concerning at least the occurrence or the correction of a consumption-relevant system error, or active switching of the restricted operating mode, and status information for a plurality of successive driving cycles is stored in the memory and used, at least in part, for the misuse assessment.

5. The method according to claim 1, wherein in the activated restricted operating mode a number of remaining engine starting operations allowed for normal vehicle operation or a value of a remaining travel distance is decremented, beginning with a predefined starting value.

6. The method according to claim 1, wherein during normal operation, when correction of a system error is detected a deactivation of the activated restricted operating mode is allowed only when the misuse assessment shows that no misuse is present, or a detected error correction is considered invalid if the misuse assessment shows that misuse is present.

7. The method according to claim 2, wherein during normal operation, when correction of a system error is detected a deactivation of the activated restricted operating mode is allowed only when the misuse assessment shows that no misuse is present, or a detected error correction is considered invalid if the misuse assessment shows that misuse is present.

8. The method according to claim 3, wherein during normal operation, when correction of a system error is detected a deactivation of the activated restricted operating mode is allowed only when the misuse assessment shows that no misuse is present, or a detected error correction is considered invalid if the misuse assessment shows that misuse is present.

9. The method according to claim 1, wherein a check for consumption-relevant system errors relevant for activating, continuing, or deactivating the restricted operating mode requires presence of a driving cycle that is assessed as valid, using predefined values for at least a minimum travel duration, a minimum travel distance, a minimum vehicle speed, or an engine standstill duration in a driving cycle or between two driving cycles.

10. The method according to claim 2, wherein a check for consumption-relevant system errors relevant for activating, continuing, or deactivating the restricted operating mode requires presence of a driving cycle that is assessed as valid, using predefined values for at least a minimum travel duration, a minimum travel distance, a minimum vehicle speed, or an engine standstill duration in a driving cycle or between two driving cycles.

11. The method according to claim 3, wherein a check for consumption-relevant system errors relevant for activating, continuing, or deactivating the restricted operating mode requires presence of a driving cycle that is assessed as valid, using predefined values for at least a minimum travel duration, a minimum travel distance, a minimum vehicle speed, or an engine standstill duration in a driving cycle or between two driving cycles.

12. The method according to claim 1, wherein status information stored in the memory of the diagnostic unit concerning presence of a valid driving cycle or concerning active switching of the restricted operating mode of a plurality of preceding driving cycles is used for the misuse assessment.

13. The method according to claim 2, wherein status information stored in the memory of the diagnostic unit concerning presence of a valid driving cycle or concerning active switching of the restricted operating mode of a plurality of preceding driving cycles is used for the misuse assessment.

14. The method according to claim 3, wherein status information stored in the memory of the diagnostic unit concerning presence of a valid driving cycle or concerning active switching of the restricted operating mode of a plurality of preceding driving cycles is used for the misuse assessment.

15. The method according to claim 9, wherein for the misuse assessment a characteristic number is provided that is redetermined at least for each valid driving cycle, and misuse is considered to be present when the characteristic number reaches or exceeds a predefined limit value.

16. The method according to claim 10, wherein for the misuse assessment a characteristic number is provided that is redetermined at least for each valid driving cycle, and misuse is considered to be present when the characteristic number reaches or exceeds a predefined limit value.

17. The method according to claim 12, wherein for the misuse assessment a characteristic number is provided that is redetermined at least for each valid driving cycle, and misuse is considered to be present when the characteristic number reaches or exceeds a predefined limit value.

18. The method according to claim 13, wherein for the misuse assessment a characteristic number is provided that is redetermined at least for each valid driving cycle, and misuse is considered to be present when the characteristic number reaches or exceeds a predefined limit value.

19. The method according to claim 15, wherein the characteristic number is correlated with the number of detected events regarding the occurrence and the correction of system errors.

20. The method according to claim 17, wherein the characteristic number is correlated with the number of detected events regarding the occurrence and the correction of system errors.

21. The method according to claim 15, wherein the characteristic number that is determined in at least each valid driving cycle is stored in a memory location of the memory of the diagnostic unit associated with the particular driving cycle, and the value of the characteristic number for the preceding driving cycle is used for determining the characteristic number associated with a particular driving cycle.

22. The method according to claim 17, wherein the characteristic number that is determined in at least each valid driving cycle is stored in a memory location of the memory of the diagnostic unit associated with the particular driving cycle, and the value of the characteristic number for the preceding driving cycle is used for determining the characteristic number associated with a particular driving cycle.

23. The method according to claim 19, wherein the characteristic number that is determined in at least each valid driving cycle is stored in a memory location of the memory of the diagnostic unit associated with the particular driving cycle, and the value of the characteristic number for the preceding driving cycle is used for determining the characteristic number associated with a particular driving cycle.

24. The method according to claim 20, wherein the characteristic number that is determined in at least each valid driving cycle is stored in a memory location of the memory of the diagnostic unit associated with the particular driving cycle, and the value of the characteristic number for the preceding driving cycle is used for determining the characteristic number associated with a particular driving cycle.