Spark advance controller and production machine of spark advance control logic in internal combustion engine

1. A spark advance controller in an internal combustion engine, comprising means for detecting operating conditions of said internal combustion engine,

and means for deciding a spark advance with computation using a produced regression model approximating spark advance control map data depending on the detected operating conditions,

wherein said regression model is a polynomial made up of at least one of a term including only an engine speed, a term including only a load, at least one of a term including only a modification variable, an interaction term including the engine speed and the load, an interaction term including the modification variable and the engine speed, an interaction term including the modification variable and the load, and an interaction term including the engine speed, the load and the modification variable.

2. The spark advance controller in the internal combustion engine according to claim 1 , wherein the regression model is divided into a reference function and a modification function, and the spark advance is decided as the sum of a spark advance reference value computed by the reference function and a spark advance modification value computed by the modification function.

3. The spark advance controller in the internal combustion engine according to claim 2 , wherein said modification variable includes an operating characteristic value of an intake valve, and the spark advance modification value is computed based on the operating characteristic of the intake valve by using the modification function with the operating characteristic value of the intake valve set as the modification variable.

4. The spark advance controller in the internal combustion engine according to claim 2 , wherein said modification variable includes an intake temperature, and the spark advance modification value is computed based on the intake temperature by using the modification function with the intake temperature set as said modification variable.

5. The spark advance controller in the internal combustion engine according to claim 2 , wherein said modification variable includes an equivalence ratio, and the spark advance modification value is computed based on the equivalence ratio by using the modification function with the equivalence ratio set as the modification variable.

6. The spark advance controller in the internal combustion engine according to claim 2 , wherein said modification variable includes an EGR (Exhaust Gas Recirculation) rate, and the spark advance modification value is computed based on the EGR rate by using the modification function with the EGR rate set as the modification variable.

7. The spark advance controller in the internal combustion engine according to claim 2 , wherein when there are a plurality of modification variables, the spark advance modification value is computed based on each of the modification variables, and the total sum of the respective spark advance modification values computed for all the modification variables is set as a total spark advance modification value.

8. The spark advance controller in the internal combustion engine according to claim 2 , wherein said reference function is defined as a dual and third-degree polynomial in which the engine speed and the load are independent variables, and said modification function is defined as a triple and third-degree polynomial in which the engine speed, the load and the modification variable are independent variables.

9. The spark advance controller in the internal combustion engine according to claim 1 , wherein the spark advance is decided as the sum of an MBT (Minimum spark advance for Best Torque) computed by using an approximated MBT regression model and a knock retard computed by using an approximated knock-retard regression model.