Cylinder air charge estimation using observer-based adaptive control

• US 6,363,316 B1
• Filed: 08/21/2000
• Issued: 03/26/2002
• Est. Priority Date: 05/13/2000
• Status: Expired due to Fees

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Robichaux, Jerry Dean, Soliman, Ihab S., Pallett, Tobias John
• Primary Examiner(s): Kwon, John
• Assistant Examiner(s): Vo, Hieu T.
• Application Number:
  US09/642,958
• Time in Patent Office: 582 Days
• Field of Search: 701/104, 701/114, 701/115, 701/102, 123/399, 123/361, 123/402, 123/403, 123/478, 123/480, 123/488, 123/494, 731/173, 731/182
• US Class Current: 701/104
• CPC Class Codes: F02D 11/105 characterised by the function converting demand to actuation, e.g. a map indicating relations between an accelerator pedal position and throttle valve opening or target engine torque
• CPC Class Codes: F02D 2041/1416 Observer
• 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 41/1402 Adaptive control
• CPC Class Codes: F02D 41/18 by measuring intake air flow

Abstract

A system and method for controlling an internal combustion engine to improve air/fuel ratio control particularly during transient operating modes include estimating cylinder air charge during a future fuel injection event. The system and method use a dynamic airflow actuator position model to determine future actuator position which is then used by an airflow model and manifold filling model to provide the estimated future cylinder air charge. The system and method use observer-based and adaptive control to compensate for modeling errors and sensor dynamics while assuring stability and accurate prediction of airflow actuator position and airflow.

Claims

1. A system for controlling an internal combustion engine having a plurality of cylinders, the system comprising:

at least one electronically controlled airflow actuator;

at least one actuator position sensor for providing a signal indicative of position of one or more of the electronically controlled airflow actuators;

an airflow sensor for providing a signal indicative of intake airflow;

a controller in communication with the at least one electronically controlled airflow actuator, the at least one position sensor, and the airflow sensor, the controller generating an estimate of cylinder air charge for a future fuel injection event based on a dynamic actuator model for the at least one airflow actuator and modifying parameters of the dynamic actuator model based on a difference between an estimated current position of the at least one airflow actuator and the signal provided by the actuator position sensor.

2. The system of claim 1 wherein the controller generates an estimate of future airflow based on a future actuator position determined by the dynamic actuator model, air charge temperature, barometric pressure, and manifold pressure.

3. The system of claim 1 wherein the at least one electronically controlled airflow actuator comprises an electronically controlled throttle valve.

4. The system of claim 1 wherein the at least one electronically controlled airflow actuator comprises a plurality of intake valves or exhaust valves.

5. A computer readable storage medium having stored data representing instructions executable by a computer to control an internal combustion engine, the computer readable storage medium comprising:

instructions for estimating future throttle valve position corresponding to a future fuel injection event using a throttle valve position model;

instructions for estimating current throttle valve position using the throttle valve position model;

instructions for adjusting the throttle valve position model based on a difference between the estimated current throttle valve position and a measured throttle valve position;

instructions for estimating a future intake airflow corresponding to the estimated future throttle valve position; and

instructions for estimating cylinder air charge based on a manifold filling model for the estimated intake airflow, the cylinder air charge corresponding to the future fuel injection event to improve the air/fuel ratio control during transient operating conditions.

6. The computer readable storage medium of claim 5 further comprising instructions for determining duration of a future fuel injection event based on a desired air/fuel ratio and the estimated cylinder air charge corresponding to the future fuel injection event.

7. The computer readable storage medium of claim 5 further comprising:

instructions for estimating a current intake airflow corresponding to the estimated current throttle valve position;

instructions for comparing the estimated current intake airflow with a measured intake airflow to generate at least one correction factor; and

instructions for adjusting the estimated future intake airflow based on the at least one correction factor.

8. A method for controlling an internal combustion engine having at least one intake airflow actuator for regulating airflow into at least one cylinder, the method comprising:

predicting position of the airflow actuator using an actuator model, the position corresponding to a subsequent injection of fuel into the cylinder; and

estimating air charge in the cylinder for the subsequent injection of fuel based on the predicted position of the airflow actuator.

9. The method of claim 8 further comprising:

estimating intake airflow for the subsequent injection of fuel using an airflow model based on the predicted position of the airflow actuator.

10. The method of claim 9 wherein the step of estimating air charge in the cylinder comprises estimating air charge in the cylinder based on the estimated intake airflow.

11. The method of claim 9 further comprising:

estimating current intake airflow based on an estimated current position of the airflow actuator as determined by the actuator model;

comparing the estimated current intake airflow to a measured intake airflow to generate an airflow modeling error; and

adjusting the airflow model based on the airflow modeling error.

12. The method of claim 11 wherein the step of comparing comprises filtering the estimated current intake airflow using a filter which simulates response characteristics of an airflow sensor used to determine the measured intake airflow.

13. The method of claim 9 further comprising:

estimating current intake airflow based on an estimated current position of the airflow actuator as determined by the actuator model;

comparing the estimated current intake airflow to a measured intake airflow to generate an airflow modeling error; and

correcting output of the airflow model based on the airflow modeling error.

14. The method of claim 8 further comprising:

estimating a current position of the airflow actuator using the actuator model;

comparing the estimated current position of the airflow actuator to a measured position of the airflow actuator to generate an actuator modeling error; and

adjusting the actuator model based on the actuator modeling error.

15. The method of claim 8 wherein the step of predicting comprises predicting position of a throttle valve.

16. The method of claim 8 wherein the step of predicting comprises predicting position of at least one intake or exhaust valve.

17. The method of claim 8 further comprising:

estimating current cylinder air charge based on a manifold filling model corresponding to an estimated current position of the airflow actuator as determined by the actuator model and an estimated current intake airflow as determined by the airflow model.

18. The method of claim 17 further comprising:

generating a second estimate of current cylinder air charge based on a measured intake airflow using the manifold filling model;

comparing the second estimate of current cylinder air charge with the estimate based on the actuator and airflow models to generate a manifold filling modeling error; and

adjusting estimated integrated mass airflows determined by the airflow model based on the manifold filling modeling error.

19. A method for controlling an internal combustion engine having an electronically controlled throttle valve to improve air/fuel ratio control during transient operating conditions, the method comprising:

estimating future throttle valve position corresponding to a future fuel injection event using a throttle valve position model;

estimating current throttle valve position using the throttle valve position model;

adjusting the throttle valve position model based on a difference between the estimated current throttle valve position and a measured throttle valve position;

estimating a future intake airflow corresponding to the estimated future throttle valve position; and

estimating cylinder air charge based on a manifold filling model for the estimated intake airflow, the cylinder air charge corresponding to the future fuel injection event to improve the air/fuel ratio control during transient operating conditions.

20. The method of claim 19 further comprising:

determining duration for a future fuel injection event based on a desired air/fuel ratio and the estimated cylinder air charge corresponding to the future fuel injection event.

21. The method of claim 19 further comprising:

estimating a current intake airflow corresponding to the estimated current throttle valve position;

comparing the estimated current intake airflow with a measured intake airflow to generate at least one correction factor; and

adjusting the estimated future intake airflow based on the at least one correction factor.

22. The method of claim 21 wherein the step of comparing comprises:

comparing the estimated current intake airflow with a measured intake airflow to generate at least one correction factor for a corresponding optimization method.

23. The method of claim 19 wherein the step of estimating a future intake airflow comprises estimating the future intake airflow using a regressed airflow model.

24. The method of claim 19 wherein the step of estimating a future intake airflow comprises estimating a future intake airflow based on current indicators for barometric pressure, air charge temperature, and manifold pressure.

25. The method of claim 19 further comprising:

estimating cylinder air charge corresponding to current throttle valve position and associated current airflow determined by the throttle valve position model and airflow model, respectively;

comparing the estimated cylinder air charge to a second estimate generated using the manifold filling model and a measured airflow to generate a manifold filling model error; and

modifying the estimated future cylinder air charge based on the manifold filling model error.