System and method for a pumping torque estimation model for all air induction configurations
View Patent ↗A system and method for controlling an engine involves providing a pumping torque estimation model. The model distinguishes between pumping losses due to throttling and pumping losses due to valve flow losses. The model is implemented by a pair of look-up tables. The data in each look-up table reflect Pumping Mean Effective Pressure (PMEP), which is indicative of the pumping work. The throttling loss table provides a first contribution based on an engine delta pressure. The valve flow loss table provides a second contribution based on an engine speed and a relative airload. The first and second contributions are summed and then multiplied by a predetermined factor to convert the pumping work (PMEP) into pumping torque. The model will work with naturally-aspirated, turbo-charged and super-charged air induction configurations and provides improved altitude compensation. The model will also work with both spark-ignition and compression-ignition configurations.
1. A method of determining a pumping torque of an internal combustion engine having a predetermined air induction configuration, comprising the steps of:
determining an engine speed, an engine delta pressure, and a relative engine airload;
calculating a first contribution based on the engine delta pressure using first predetermined data, the first contribution corresponding to throttling loss;
calculating a second contribution based on the engine speed and the engine airload using second predetermined data, the second contribution corresponding to valve flow loss; and
determining a pumping torque based on the first and second contributions.
2. The method of claim 1 wherein said step of determining engine delta pressure comprises the substeps of:
determining an air intake pressure (P int );
determining an exhaust pressure (P exh );
determining a difference between the intake and exhaust pressures (P exh −P int ).
3. The method of claim 1 wherein said step of determining the engine airload comprises the substeps of:
determining a reference cylinder air mass taken at a predetermined volumetric efficiency (VE), predetermined intake pressure and predetermined temperature;
determining an actual cylinder air mass; and
dividing the actual cylinder air mass by the reference cylinder air mass to obtain the engine airload (%).
4. The method of claim 1 said step of determining the first contribution includes the substep of:
obtaining a first pumping mean effective pressure (PMEP) value from a first data structure containing the first predetermined data based on the engine pressure delta.
5. The method of claim 4 wherein said step of determining the second contribution includes the substep of:
obtaining a second pumping mean effective pressure (PMEP) value from a second data structure containing the second predetermined data based on the engine speed and the engine airload.
6. The method of claim 5 wherein said step of determining the pumping torque includes the sub-steps of:
summing the first and second PMEP values to obtain an aggregate PMEP value; and
multiplying the aggregate PMEP value by a predetermined conversion factor to obtain the pumping torque.
7. The method of claim 6 wherein the predetermined conversion factor corresponds to V eng /4*π where V eng is the total displacement volume of the engine.
8. A method of controlling an internal combustion engine having a predetermined air induction configuration, comprising the steps of:
determining an engine speed, an engine delta pressure, and a relative engine airload;
calculating a first contribution based on the engine delta pressure using first predetermined data, the first contribution corresponding to throttling loss;
calculating a second contribution based on the engine speed and the engine airload using second predetermined data, the second contribution corresponding to valve flow loss;
determining a pumping torque based on the first and second contributions; and
controlling the engine based on the determined pumping torque.
9. The method of claim 8 wherein said step of determining engine delta pressure comprises the substeps of:
determining an air intake pressure (P int );
determining an exhaust pressure (P exh );
determining a difference between the intake and exhaust pressures (P exh −P int ).
10. The method of claim 8 wherein said step of determining the engine airload comprises the substeps of:
determining a reference cylinder air mass taken at a predetermined volumetric efficiency (VE), predetermined intake pressure and predetermined temperature;
determining an actual cylinder air mass; and
dividing the actual cylinder air mass by the reference cylinder air mass to obtain the engine airload (%).
11. The method of claim 8 said step of determining the first contribution includes the substep of:
obtaining a first pumping mean effective pressure (PMEP) value from a first data structure containing the first predetermined data based on the engine pressure delta.
12. The method of claim 11 wherein said step of determining the second contribution includes the substep of:
obtaining a second pumping mean effective pressure (PMEP) value from a second data structure containing the second predetermined data based on the engine speed and the engine airload.
13. The method of claim 12 wherein said step of determining the pumping torque includes the sub-steps of:
summing the first and second PMEP values to obtain an aggregate PMEP value; and
multiplying the aggregate PMEP value by a predetermined conversion factor to obtain the pumping torque.
14. The method of claim 13 wherein the predetermined conversion factor corresponds to V eng /4*π where V eng is the total displacement volume of the engine.