Hybrid vehicle exhaust diagnostics

• US 9,296,390 B2
• Filed: 03/15/2013
• Issued: 03/29/2016
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Martin, Douglas Raymond, Taylor, Richard Paul, Smith, Matthew D.
• Primary Examiner(s): Low, Lindsay
• Assistant Examiner(s): JIN, GEORGE C.
• Application Number:
  US13/841,206
• Publication Number:
  US 20140277998A1
• Time in Patent Office: 1,110 Days
• Field of Search: 123/672, 123/320, 123/325, 123/332, 123/333, 123/339.12, 123/394, 123/443, 123/23.31, 123/23.32, 123/675, 123/682, 123/690, 123/198.F, 73/10.6, 731/147.3, 701/109, 701/110, 701/112, 602/76, 602/77, 180/65.28, 180/65.21
• US Class Current: 1/1
• CPC Class Codes: B60W 20/50 Control strategies for responding to system failures, e.g. for fault diagnosis, failsafe operation or limp mode
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2710/0622 Air-fuel ratio
• 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 11/007 the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus
• CPC Class Codes: F01N 2550/02 Catalytic activity of catalytic converters
• CPC Class Codes: F01N 2560/025 for measuring or detecting O2, e.g. lambda sensors
• 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: F02D 2200/021 Engine temperature
• CPC Class Codes: F02D 2200/602 Pedal position
• CPC Class Codes: F02D 41/123 the fuel injection being cut-off
• CPC Class Codes: F02D 41/1475 Regulating the air fuel ratio at a value other than stoichiometry
• CPC Class Codes: F02D 41/1495 Detection of abnormalities in the air/fuel ratio feedback system
• CPC Class Codes: F02D 41/222 relating to the failure of sensors or parameter detection devices
• CPC Class Codes: F02N 11/0829 related to special engine control, e.g. giving priority to engine warming-up or learning
• CPC Class Codes: F02N 2200/0801 Vehicle speed
• CPC Class Codes: F02N 2200/101 Accelerator pedal position
• CPC Class Codes: Y02T 10/40 Engine management systems
• CPC Class Codes: Y10S 903/904 Component specially adapted for hev

Abstract

Methods are provided for performing diagnostic routines in a hybrid vehicle. In one example approach, a method for operating a hybrid vehicle comprises inhibiting engine shutdown and enabling deceleration fuel shut off to perform a monitoring test while a vehicle speed is above a threshold speed.

Claims

1. A method for a hybrid vehicle with an engine, comprising:

inhibiting engine shutdown and enabling deceleration fuel shut off to perform a monitoring test while a vehicle speed is above a threshold speed,

the monitoring test including monitoring a rich to lean transition upstream and downstream of a catalyst in an exhaust of the vehicle, inhibiting engine shutdown when exhaust gas sensors upstream and downstream of the catalyst are reading rich, and not inhibiting engine shutdown when exhaust gas sensors upstream and downstream of the catalyst are reading lean.

2. The method of claim 1, wherein inhibiting engine shutdown to perform the monitoring test is performed in response to an engine pull-down request while the engine is running and an engine temperature is greater than a threshold temperature.

3. The method of claim 2, wherein the engine pull-down request is generated in response to a driver tip-out.

4. The method of claim 1, further comprising shutting down the engine after the monitoring test is complete.

5. The method of claim 1, wherein the monitoring test includes monitoring a rich to lean transition at an air/fuel sensor in the exhaust of the vehicle.

6. The method of claim 5, further comprising indicating sensor degradation in response to the rich to lean transition at the air/fuel sensor.

7. The method of claim 1, further comprising indicating catalyst degradation in response to the rich to lean transition downstream of the catalyst.

8. The method of claim 1, further comprising:

in response to an engine pull-down request when a vehicle speed is greater than a first threshold speed;

inhibiting engine shutdown;

enabling deceleration fuel shut off;

monitoring a rich to lean transition at an air/fuel sensor in the exhaust of the vehicle; and

indicating sensor degradation based on the rich to lean transition at the air/fuel sensor; and

in response to an engine pull-down request when a vehicle speed is greater than a second threshold speed which is less than the first threshold speed;

inhibiting engine shutdown;

enabling deceleration fuel shut off;

monitoring a rich to lean transition upstream and downstream of the catalyst in the exhaust of the vehicle; and

indicating catalyst degradation based on the rich to lean transition upstream and downstream of the catalyst.

9. A method for a hybrid vehicle, comprising:

in response to an engine pull-down request when a vehicle speed is greater than a threshold speed;

inhibiting engine shutdown;

enabling deceleration fuel shut off with the engine still spinning;

monitoring a rich to lean transition in an exhaust of the vehicle, including monitoring a rich to lean transition upstream and downstream of a catalyst in the exhaust of the vehicle where engine shutdown is inhibited in response to exhaust gas sensors upstream and downstream of the catalyst reading rich and not inhibiting engine shutdown when exhaust gas sensors upstream and downstream of the catalyst are reading lean; and

indicating a degradation based on the rich to lean transition.

10. The method of claim 9, wherein the engine pull-down request includes a driver tip-out.

11. The method of claim 9, further comprising shutting down the engine after monitoring the rich to lean transition for a duration if the request is still present.

12. The method of claim 9, wherein monitoring a rich to lean transition in an exhaust of the vehicle includes monitoring a rich to lean transition at an air/fuel sensor in the exhaust of the vehicle.

13. The method of claim 9, further comprising not inhibiting engine shutdown while an engine shutdown has been inhibited for a duration greater than a threshold.

14. A method for a hybrid vehicle, comprising:

in response to an engine pull-down request when a vehicle speed is greater than a first threshold speed;

inhibiting engine shutdown;

enabling deceleration fuel shut off;

monitoring a rich to lean transition at an air/fuel sensor in an exhaust of the vehicle;

indicating sensor degradation based on the rich to lean transition at the air/fuel sensor; and

shutting down the engine after monitoring the rich to lean transition at the air/fuel sensor for a duration; and

in response to an engine pull-down request when the vehicle speed is greater than a second threshold speed which is less than the first threshold speed;

inhibiting engine shutdown;

enabling deceleration fuel shut off;

monitoring a rich to lean transition upstream and downstream of a catalyst in the exhaust of the vehicle where engine shutdown is inhibited in response to exhaust gas sensors upstream and downstream of the catalyst reading rich and not inhibiting engine shutdown when exhaust gas sensors upstream and downstream of the catalyst are reading lean; and

indicating catalyst degradation based on the rich to lean transition upstream and downstream of the catalyst; and

shutting down the engine after monitoring the rich to lean transition upstream and downstream of the catalyst for a duration.

15. The method of claim 14, wherein the engine pull-down request is a driver tip-out.

16. The method of claim 14, wherein the vehicle is a plug-in hybrid electric vehicle.