Software air-flow meter for an internal combustion engine

• US 5,293,553 A
• Filed: 12/06/1991
• Issued: 03/08/1994
• Est. Priority Date: 02/12/1991
• Status: Expired due to Term

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Dudek, Kenneth P., White, Vincent A.
• Primary Examiner(s): Harvey, Jack B.
• Assistant Examiner(s): PIPALA, EDWARD J
• Application Number:
  US07/804,857
• Time in Patent Office: 823 Days
• Field of Search: 364/431.01, 364/431.03, 364/431.04, 364/431.05, 364/148-151, 364/510, 364/550, 364/571.01, 364/571.04, 364/571.05, 364/578, 73/117.2, 73/118.2, 123/463, 123/480, 123/488, 123/494
• US Class Current: 701/102
• CPC Class Codes: F02D 2041/1415 using a state feedback or a state space representation
• CPC Class Codes: F02D 2041/1417 Kalman filter
• 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 41/1401 characterised by the control or regulation method F02D41/1473, F02D41/1477 take precedence
• CPC Class Codes: F02D 41/18 by measuring intake air flow
• CPC Class Codes: G01F 1/86 Indirect mass flowmeters, e.g. measuring volume flow and density, temperature or pressure

Abstract

A method for accurately determining the measure of mass airflow into an internal combustion engine is implemented with a controller that determines measures of various engine parameters, determines a prediction set including at least one predicted value of a measurable engine parameter and at least one predicted value of mass airflow into the engine, determines an estimation set including at least one estimated value of mass airflow into the engine and controls the engine in response to the estimated value of mass airflow.

Claims

1. An engine - controller combination, comprising:

a vehicle engine;

means for determining measures of a set of engine parameters and for providing measurement signals indicative of said measures; and

a microprocessor control unit, including (i) means for receiving the measurement signals, (ii) means for determining a prediction set including at least one predicted value of a measurable engine parameter and at least one predicted value of mass airflow into the engine, (iii) means for determining an estimation set including at least one estimated value of mass airflow into the engine, and (iv) means for controlling the engine in response to the estimated value of mass airflow, wherein

the microprocessor control unit iteratively (i) determines the prediction set in response to (a) the measurement signals, (b) a linear model comprising a set of fixed predetermined model parameters, and (c) the estimation set, and (ii) determines the estimation set in response to (a) a present measure of the measurable engine parameter, (b) the prediction set, and (c) a correction set of fixed predetermined correction coefficients wherein the estimated value of the mass airflow into the engine is a substantially accurate measure of actual mass airflow into the engine.

2. The combination of claim 1, wherein the measurable engine parameter is manifold absolute pressure.

3. The combination of claim 1, wherein the controlling means controls fueling of the engine by developing a fuel command in response to the estimated mass airflow and outputting the fuel command to a fuel injection control unit, which fuels the engine in response to the fuel command, thereby improving engine air-fuel ratio control.

4. The combination of claim 3, wherein the measurable engine parameter is manifold, absolute pressure.

5. The combination of claim 1, wherein the controlling means controls engine spark through spark timing and dwell commands output to a spark timing control module, by developing the spark timing and dwell commands in response to the prediction set and outputting the spark timing and dwell commands to the spark timing control module.

6. The combination of claim 5, wherein the measurable engine parameter is manifold absolute pressure.

7. The combination of claim 1, wherein the controlling means controls an idle air control valve through an idle air control valve command, by developing the idle air control valve command in response to the prediction set and outputting the idle air control valve command to the idle air control valve.

8. The combination of claim 7, wherein the measurable engine parameter is manifold absolute pressure.

9. The combination of claim 1, wherein:

the prediction set of a given engine event comprises a vector X^p (k+1) where k is a present engine event, the measures of the set of engine parameters comprise a vector U(k), the estimation set comprises a vector X^e (k), and the set of fixed predetermined model parameters comprises matrices A, B, and C, the prediction set being determined by a relation;

space="preserve" listing-type="equation">X.sup.P (k+1)=AX.sup.e (k)+BU(k)+C; and

the correction set comprises a vector G, and X^p (k) and X(k) represent predicted and measured values of the measurable engine parameter at event k, respectively, the estimation set being determined by a relation;

space="preserve" listing-type="equation">X.sup.e (k)=X.sup.p (k)+G(X(k)-X.sup.p (k)).

10. The combination of claim 9, wherein the measurable engine parameter is manifold absolute pressure.

11. The combination of claim 10, wherein the set of model parameters is predetermined through statistical regression.

12. The combination of claim 10, wherein the set of model parameters is scheduled according to two independent engine parameters.

13. The combination of claim 10, wherein the correction set is predetermined through Kalman filtering.

14. The combination of claim 1, wherein the correction set is predetermined through Kalman filtering.

15. The combination of claim 1, wherein the set of engine parameters includes throttle position and engine speed.

16. The combination of claim 10, wherein the set of engine parameters includes throttle position and engine speed.

17. The combination of claim 15, wherein the set of engine parameters also includes at least one member of a set comprising:

manifold absolute pressure, idle air control valve position, exhaust gas recirculation valve position, atmospheric pressure and air temperature.

18. The combination of claim 16, wherein the set of engine parameters also includes at least one member of a set comprising:

manifold absolute pressure, idle air control valve position, exhaust gas recirculation valve position, atmospheric pressure and air temperature.

19. An engine - controller combination, comprising:

a vehicle engine;

means for determining measures of a set of engine parameters and for providing measurement signals indicative of said measures for every event k; and

a microprocessor control unit, including (i) means for receiving the measurement signals, (ii) means for determining a prediction set including at least one predicted value of a measurable engine parameter and at least one predicted value of mass airflow into the engine, (iii) means for determining an estimation set including at least one estimated value of mass airflow into the engine, and (iv) means for controlling the engine in response to the estimated value of mass airflow, wherein

the microprocessor control unit;

initializes a set of variables including the measures of the set of engine parameters and the estimation set for events preceding time k, and the prediction set for events preceding time k+1;

thereafter iteratively;

receives the measurement signals for event k;

determines an error signal in response to a difference between a measure of the measurable engine state at event k and a prediction of the measurable engine state for event k;

schedules a correction set of fixed predetermined correction coefficients in response to two of the measurement signals representing independent engine parameters;

determines the estimation set in response to the prediction set, the error signal, and the correction set;

schedules a set of fixed model parameters in response to the two measurement signals representing independent engine parameters;

determines the prediction set in response to the measurement signals for event k and preceding events, the estimation set, the set of fixed model parameters;

determines a control command in response to the estimated mass airflow; and

applies the control command to the engine.

20. The combination of claim 19, wherein the measurable engine parameter is manifold absolute pressure.

21. The combination of claim 19, wherein the set of model parameters and the correction set are scheduled from control unit memory.

22. The combination of claim 19, wherein the set of engine parameters includes throttle position and engine speed.

23. The combination of claim 20, wherein the set of engine parameters includes throttle position and engine speed.

24. The combination of claim 22, wherein the set of engine parameters also includes at least one member of a set comprising:

manifold absolute pressure, idle air control valve position, exhaust gas recirculation valve position, atmospheric pressure and air temperature.

25. The combination of claim 23, wherein the set of engine parameters also includes at least one member of a set comprising:

manifold absolute pressure, idle air control valve position, exhaust gas recirculation valve position, atmospheric pressure and air temperature.