Method to determine reference airflow actuator positions for a gasoline engine
A method to determine reference actuator positions for a gasoline engine, includes entering a base torque request, a known spark advance, a known CAM position and a known exhaust gas recirculation (EGR) valve position into an inverse torque model to generate a first iteration desired air per cylinder (APC) value. The first iteration desired APC value is passed through a deadband filter to produce a filtered first iteration desired APC signal. A Predicted As Cal (PAC) spark advance is calculated for the filtered first iteration desired APC value. The PAC spark advance and the base torque request are modified, and data from a first lookup table is entered to generate a second iteration desired APC value.
1. A method to determine reference actuator positions for a gasoline engine, including:
identifying a base torque request as a last time loop execution of each of a CAM position, an exhaust gas recirculation (EGR) valve position and a predicted spark;
applying an inverse torque model to the base torque request to generate a first iteration desired air per cylinder (APC) value;
passing the first iteration APC value through a dead band filter to minimize oscillations, thereby defining a filtered APC value;
entering multiple look-up tables with the filtered APC value, including:
looking up a desired CAM position in a CAM position look-up table; and
looking up a desired EGR valve position in an EGR valve position look-up table;
calculating a Predicted As Cal (PAC) spark advance for the desired CAM position and the desired EGR valve position;
generating a second iteration desired APC value by passing the PAC spark advance through a torque model translation; and
entering an output of the torque model translation again into the CAM position look-up table and the EGR valve position look-up table.
2. The method to determine reference actuator positions for a gasoline engine of claim 1 , further including determining a reference CAM position from the CAM position look-up table.
3. The method to determine reference actuator positions for a gasoline engine of claim 2 , further including determining a reference EGR valve position from the EGR valve position look-up table.
4. The method to determine reference actuator positions for a gasoline engine of claim 3 , further including directly commanding at least one actuator using the reference CAM position and the reference EGR valve position.
5. The method to determine reference actuator positions for a gasoline engine of claim 1 , further including entering the output of the torque model translation into a wastegate lookup table to generate a reference wastegate position.
6. The method to determine reference actuator positions for a gasoline engine of claim 1 , further including entering the output of the torque model translation into a throttle lookup table to generate a reference throttle position.
7. The method to determine reference actuator positions for a gasoline engine of claim 1 , further including adding an air conditioner load during the identifying the base torque request step.
8. The method to determine reference actuator positions for a gasoline engine of claim 7 , further including adding a generator load during the identifying the base torque request step.
9. The method to determine reference actuator positions for a gasoline engine of claim 1 , further including applying constraints to the desired CAM position to obtain a constrained desired CAM position and applying constraints to the desired EGR valve position to obtain a constrained desired EGR valve position.
10. The method to determine reference actuator positions for a gasoline engine of claim 1 , further including performing the calculating step using the constrained desired CAM position and the constrained desired EGR valve position.
11. A method to determine reference actuator positions for a gasoline engine, including:
identifying a base torque request as a last time loop execution of each of a CAM position, an exhaust gas recirculation (EGR) valve position and a predicted spark;
applying an inverse torque model to the base torque request to generate a first iteration desired air per cylinder (APC) value to approximate a desired APC value;
passing the first iteration APC value defining the desired APC value through a dead band filter to minimize oscillations thereby defining a filtered APC value;
entering multiple look-up tables with the filtered APC value, including:
looking up a desired CAM position in a CAM position look-up table; and
looking up a desired EGR valve position in an EGR valve position look-up table;
applying constraints to the desired CAM position to obtain a constrained desired CAM position and to the desired EGR valve position to obtain a constrained desired EGR valve position;
calculating a Predicted As Cal (PAC) spark advance for the constrained desired CAM position and the constrained desired EGR valve position;
generating a second iteration desired APC value by passing the PAC spark advance through a torque model translation; and
entering an output of the torque model translation into the CAM position look-up table and the EGR valve position look-up table.
12. The method for determining reference actuator positions for a gasoline engine of claim 11 , further including determining a reference CAM position from the CAM position look-up table and directly commanding at least one actuator using the reference CAM position.
13. The method for determining reference actuator positions for a gasoline engine of claim 12 , further including determining a reference EGR valve position from the EGR valve position look-up table and directly commanding at least one actuator using the reference EGR valve position.
14. The method for determining reference actuator positions for a gasoline engine of claim 11 , further including determining a spark efficiency to assume for a translation from a torque APC to a desired APC.
15. The method for determining reference actuator positions for a gasoline engine of claim 14 , further including applying the calculated Predicted As Cal (PAC) spark advance to determine a spark advance at an end of a spark event.
16. The method for determining reference actuator positions for a gasoline engine of claim 15 , further including entering lookup tables to determine each of:
a final reference intake cam position signal;
a final reference exhaust cam position signal; and
a final reference EGR position signal.
17. The method for determining reference actuator positions for a gasoline engine of claim 16 , further including modifying the desired APC second iteration signal with data from at least one wastegate lookup table to create a reference wastegate position as a function of the desired APC value.
18. The method for determining reference actuator positions for a gasoline engine of claim 17 , further including modifying the desired APC second iteration signal with data from at least one throttle lookup table to create a reference throttle position.