Granted Patent B2

US 7,032,439 · App. 10/660,036 · Granted Apr 25, 2006

Abstract

Claims (26)

1. A method of detecting misfire in an engine comprising:

detecting engine speed fluctuations;

determining a linear model for estimating engine firing events based on the engine speed fluctuations;

applying a Kalman filter to the linear model to determine parameters of the linear model; and

detecting a misfire event in the engine based on the linear model.

2. The method of claim 1 further comprising representing the linear model as a difference equation.

3. The method of claim 2 further wherein applying the Kalman filter includes estimating parameters of the difference equation.

4. The method of claim 3 wherein the linear model is an inverse linear model of a linear model of engine crankshaft speed.

5. The method of claim 4 wherein the difference equation is of the form

y ( k )= b o N ( k )+ b 1 N ( k− 1)+. . . + b m N ( k−m )+ v ( k )

where b 0 . . . b m are the model parameters and N is the engine speed at sample k, k−1, . . . k−m, where k and m are integers, and applying the Kalman filter to estimate parameters of the difference equation includes applying the Kalman filter to estimate the model parameters.

6. The method of claim 1 further comprising reformulating the linear model using standard state space systems equations.

7. The method of claim 1 further comprising determining a load compensator signal based on an engine speed and a manifold absolute pressure, wherein detecting the misfire event includes detecting the misfire event based on the firing event signal and the load compensator signal.

8. A method of detecting misfire in an engine comprising:

detecting crankshaft speed fluctuations in the engine;

determining a linear model for estimating engine firing events based on the crankshaft speed fluctuations;

representing the linear model as a difference equation;

estimating parameters of the difference equation at a Kalman filter to determine a firing event model; and

detecting a misfire event in the engine based on the firing event model.

9. A misfire detection system that detects misfire in an engine comprising:

a sensor that determines speed fluctuations of the engine;

a controller that determines a firing event model for estimating engine firing events based on the speed fluctuations of the engine and applies a Kalman filter to the model to estimate parameters of the model; and

a misfire detector that detects a misfire event based on the model.

10. A misfire detection system according to claim 9 wherein the firing event model is a difference equation.

11. A misfire detection system according to claim 10 wherein the Kalman filter estimates parameters of the difference equation.

12. The method of claim 9 wherein the controller determines a load compensator signal based on an engine speed and a manifold absolute pressure, and wherein the misfire detector detects the misfire event based on the firing event model and the load compensator signal.

Assignments (20)