Onboard diagnostic misfire detection monitor for internal combustion engines

• US 6,415,656 B1
• Filed: 05/02/2000
• Issued: 07/09/2002
• Est. Priority Date: 05/02/2000
• Status: Expired due to Fees

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Zimlich, Glenn Alden, Bidner, David Karl, Robichaux, Jerry Dean
• Primary Examiner(s): MCCALL, ERIC SCOTT
• Application Number:
  US09/563,644
• Time in Patent Office: 798 Days
• Field of Search: 731/16, 731/172, 731/173, 731/181
• US Class Current: 73/114.15
• 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 15/11 by detecting misfire
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A misfire monitoring method and system employ an indicated mean effective pressure (IMEP) parameter for misfire monitoring of an internal combustion engine of a vehicle. The method and system include determining displacement and torque of the engine. An indicated mean effective pressure (IMEP) parameter is then calculated for the engine. The indicated mean effective pressure (IMEP) parameter is engine torque divided by engine displacement. A misfire monitor monitors the indicated mean effective pressure (IMEP) parameter to detect misfire. The method and system include determining maximum indicated mean effective pressure (IMEP_MAX) parameter for the engine. A normalized indicated mean effective pressure (IMEP_LOAD) parameter for the engine is then calculated. The normalized indicated mean effective pressure (IMEP_LOAD) parameter is the indicated mean effective pressure (IMEP) parameter divided by the maximum indicated mean effective pressure (IMEP_MAX) parameter. Monitoring the indicated mean effective pressure (IMEP) parameter to detect misfire includes monitoring the normalized indicated mean effective pressure (IMEP_LOAD) parameter to detect misfire.

Claims

1. A method for detecting misfire in an internal combustion engine of a vehicle, the method comprising:

determining displacement of the engine;

determining torque of the engine;

calculating an indicated mean effective pressure (IMEP) parameter for the engine, wherein the indicated mean effective pressure (IMEP) parameter is engine torque divided by engine displacement;

determining maximum indicated mean effective pressure (IMEP_MAX) parameter for the engine;

calculating a normalized indicated mean effective pressure (IMEP_LOAD) parameter for the engine, wherein the normalized indicated mean effective pressure (IMEP_LOAD) parameter is the indicated mean effective pressure (IMEP) parameter divided by the maximum indicated mean effective pressure (IMEP_MAX) parameter; and

monitoring the indicated mean effective pressure (IMEP) parameter to detect misfire.

2. The method of claim 1 wherein:

monitoring the indicated mean effective pressure (IMEP) parameter to detect misfire includes monitoring the normalized indicated mean effective pressure (IMEP_LOAD) parameter to detect misfire.

3. The method of claim 1 wherein:

monitoring the indicated mean effective pressure (IMEP) parameter includes monitoring changes of the indicated mean effective pressure (IMEP) parameter to detect misfire.

4. A method for detecting misfire in an internal combustion engine of a vehicle, the method comprising:

determining displacement of the engine;

determining torque of the engine;

calculating an indicated mean effective pressure (IMEP) parameter for the engine, wherein the indicated mean effective pressure (IMEP) parameter is engine torque divided by engine displacement;

determining maximum indicated mean effective pressure (IMEP_MAX) parameter for the engine;

calculating a normalized indicated mean effective pressure (IMEP_LOAD) parameter for the engine, wherein the normalized indicated mean effective pressure (IMEP_LOAD) parameter is the indicated mean effective pressure (IMEP) parameter divided by the maximum indicated mean effective pressure (IMEP_MAX) parameter; and

monitoring the normalized indicated mean effective pressure (IMEP_LOAD) parameter to detect misfire.

5. The method of claim 4 wherein:

the internal combustion engine is a direct injection internal combustion engine.

6. The method of claim 4 wherein:

monitoring the normalized indicated mean effective pressure (IMEP_LOAD) parameter to detect misfire includes monitoring changes of the normalized indicated mean effective pressure (IMEP_LOAD) parameter to detect misfire.

7. A system detecting misfire in an internal combustion engine of a vehicle, the system comprising:

means for determining displacement of the engine;

means for determining torque of the engine;

a processor for calculating an indicated mean effective pressure (IMEP) parameter for the engine, wherein the indicated mean effective pressure (IMEP) parameter is engine torque divided by engine displacement, wherein the processor calculates a maximum indicated mean effective pressure (IMEP_MAX) parameter for the engine and a normalized indicated mean effective pressure (IMEP_LOAD) parameter for the engine, wherein the normalized indicated mean effective pressure (IMEP_LOAD) parameter is the indicated mean effective pressure (IMEP) parameter divided by the maximum indicated mean effective pressure (IMEP_MAX) parameter; and

a misfire monitor for monitoring the indicated mean effective pressure (IMEP) parameter to detect misfire.

8. The system of claim 7 wherein:

the internal combustion engine is a direct injection internal combustion engine.

9. The system of claim 7 wherein:

the misfire monitor monitors the normalized indicated mean effective pressure (IMEP_LOAD) parameter to detect misfire.

10. The system of claim 7 wherein:

the misfire monitor monitors changes of the indicated mean effective pressure (IMEP) parameter to detect misfire.