DIAGNOSIS OF SENSOR FAILURE IN AIRFLOW-BASED ENGINE CONTROL SYSTEM

• US 20100042284A1
• Filed: 08/12/2008
• Published: 02/18/2010
• Est. Priority Date: 08/12/2008
• Status: Active Grant

• Current Assignee: Southwest Research Institute
• Original Assignee: Southwest Research Institute
• Inventors: Sasaki, Shizuo
• Granted Patent: US 8,521,354 B2
• Time in Patent Office: Days
• US Class Current: 701/29
• CPC Class Codes: F02D 2041/1433 using a model or simulation of the system
• CPC Class Codes: F02D 2200/0402 the parameter being determined by using a model of the engine intake or its components
• CPC Class Codes: F02D 2200/0406 Intake manifold pressure
• CPC Class Codes: F02D 2200/0414 Air temperature
• CPC Class Codes: F02D 41/0072 Estimating, calculating or determining the EGR rate, amount or flow sensors in EGR systems F02M26/45
• CPC Class Codes: F02D 41/144 Sensor in intake manifold
• CPC Class Codes: F02D 41/18 by measuring intake air flow
• CPC Class Codes: F02D 41/222 relating to the failure of sensors or parameter detection devices
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

An air-flow based control system for an internal combustion engine has various sensors that are used to calculate various control commands. By comparing pairs of values calculated from different sensors, errors in connection with the sensors can be detected.

Claims

1. A method of diagnosing failure in an airflow-based control system for an internal combustion engine, wherein the control system accesses an EGR rate map to control the EGR rate of the engine, comprising:

obtaining values for the following parameters;

airflow mass, intake manifold oxygen concentration, intake manifold pressure, intake manifold temperature, and exhaust oxygen concentration;

calculating a first EGR rate based on the airflow mass, intake manifold pressure, and intake manifold temperature;

calculating a second EGR rate based on the intake manifold oxygen concentration and exhaust oxygen concentration;

comparing the first EGR rate to a mapped EGR rate from the EGR rate map;

comparing the second EGR rate to the mapped EGR rate;

comparing the first EGR rate to the second EGR rate;

generating EGR rate failure data if the first and second EGR rate matches but the mapped EGR rate map does not match;

generating sensor failure data used for the first EGR rate calculation if the mapped EGR rate and the second EGR rate match but the first EGR rate does not match; and

generating sensor failure used for the second EGR rate calculation if the mapped EGR rate and first EGR rate match but the second EGR rate does not match.

2. The method of claim 1, further comprising the step of analyzing the results of the comparing step to determine if the failure is in connection with the intake pressure sensor.

3. The method of claim 1, further comprising the step of obtaining a measured airflow mass value;

of using the second EGR rate, the intake manifold temperature, and the intake manifold pressure to calculate a calculated airflow mass value;

comparing the measured airflow mass value to the calculated airflow mass value; and

generating airflow mass failure data if these values do not match.

4. The method of claim 3, further comprising the step of generating airflow mass failure data only if the second EGR rate and the mapped EGR rate are matched.

5. The method of claim 1, wherein the comparing steps are performed at the same engine speed.

6. The method of claim 1, wherein the comparing steps are performed at the same airflow mass condition of the engine.

7. A method of diagnosing failure in connection with a mass airflow sensor used in an airflow-based engine control system for an internal combustion engine, comprising:

obtaining a measured airflow mass value from the mass airflow sensor;

obtaining values for the following input parameters;

intake manifold pressure, intake manifold temperature, and the EGR rate;

calculating a calculated airflow mass value based on the input parameters;

comparing the measured airflow mass value to the calculated airflow mass value; and

generating airflow mass sensor failure data if the comparing step does not result in a match.

8. The method of claim 7, wherein the EGR rate is obtained by calculations based on intake O2 concentration and exhaust O2 concentration.

9. The method of claim 7, further comprising the steps of accessing a mapped EGR rate from a stored EGR map, and of generating airflow mass failure data only if the EGR rate and the mapped EGR rate are matched.

10. A method of diagnosing failure in connection with the EGR system of an airflow-based engine control system that uses an EGR base map to determine the EGR rate, comprising:

calculating the EGR rate at a given engine speed and intake O2 mass value;

comparing the calculated EGR rate with the EGR rate provided by the EGR base map for the same engine speed and intake O2 mass value;

wherein the step of calculating the EGR rate is performed on the basis of the airflow mass, intake manifold pressure, and intake manifold temperature.

11. A method of diagnosing failure in connection with the EGR system of an airflow-based engine control system that uses an EGR base map to determine the EGR rate, comprising:

calculating the EGR rate at a given engine speed and intake O2 mass value;

comparing the calculated EGR rate with the EGR rate provided by the EGR base map for the same engine speed and intake O2 mass value;

wherein the step of calculating the EGR rate is performed on the basis of the intake manifold O2 concentration and exhaust O2 concentration.

12. A method of diagnosing failure in connection with the intake manifold O2 concentration sensor of an airflow-based engine control system, comprising:

calculating a current EGR rate value on the basis of the airflow mass, intake manifold pressure, and intake manifold temperature;

calculating a current in-cylinder O2 mass value based on the EGR rate value;

calculating a calculated intake manifold O2 concentration value, based on the results of the preceding steps;

receiving a measured intake manifold O2 concentration value;

comparing the calculated intake manifold O2 concentration value to the measured intake manifold O2 concentration value; and

generating failure data if the comparing step does not result in a match.

13. A method of diagnosing failure in connection with fuel injection quantity commands generated by an airflow-based engine control system, comprising:

receiving sensor values for airflow mass, intake manifold O2 concentration, and exhaust O2 concentration;

using the sensor values to calculate a calculated fuel injection quantity value; and

comparing the calculated fuel injection quantity value to the value represented by the fuel injection quantity command.

14. The method of claim 13, further comprising correcting the fuel injection quantity command based on the results of the calculating step.