Airflow-based output torque estimation for multi-displacement engine
View Patent ↗A method for estimating an output torque generated by a multi-displacement engine operating in a partial-displacement mode includes multiplying a measure representing a mass air flow through the engine's intake manifold by a engine-speed-based mass-air-flow-to-torque conversion factor, and thereafter summing the product with a torque offset value likewise based on engine speed data, to obtain a base indicated potential output torque. The base indicated potential output torque is then multiplied with a torque-based efficiency conversion factor representing at least one of a partial-displacement mode spark efficiency, fuel-air-ratio efficiency, and exhaust gas recirculation efficiency, and the resulting product is summed with a torque-based frictional loss measure to obtain the desired estimated engine output torque. The estimated engine output torque is particularly useful in determining whether a transition from the partial-displacement engine operating mode to a full-displacement engine operating mode is desired.
1. A method for estimating an output torque generated by a multi-displacement internal combustion engine operating in a partial-displacement mode, the engine including an intake manifold and an engine speed sensor generating engine speed data, the method comprising:
providing a first measure representing a mass air flow through the intake manifold;
determining a mass-air-flow-to-torque conversion factor and a mass-air-flow-to-torque offset based on the engine speed data;
multiplying the first measure by the conversion factor to obtain a second measure representing a pre-offset base indicated torque;
summing the second measure with the torque offset to obtain a third measure representing a base indicated potential torque; and
multiplying the base indicated potential torque measure with a torque-based efficiency conversion factor representing at least one of a spark efficiency measure, a fuel-air-ratio efficiency measure, and an exhaust gas recirculation efficiency measure, to obtain a third measure representing an efficiency-corrected indicated potential torque measure.
2. The method of claim 1 , wherein providing includes determining the first measure based on a detected manifold air pressure and the engine speed data.
3. The method of claim 1 , wherein the first measure further represents a maximum mass air flow through the intake manifold, and wherein determining the first measure is further based on at least one of a barometric pressure, an inlet air temperature, an engine coolant temperature, and an exhaust gas oxygen content.
4. The method of claim 3 , wherein the first measure represents the maximum mass air flow through the intake manifold in a full-displacement engine operating mode, and wherein the first measure is further determined by multiplying the maximum mass air flow by a partial-displacement correction factor.
5. The method of claim 1 , further including calculating an average engine speed based on the engine speed data, and wherein determining the mass-air-flow-to-torque conversion factor is based on the average engine speed, and determining the torque offset is based on the average engine speed.
6. The method of claim 1 , wherein determining the mass-air-flow-to-torque conversion factor includes retrieving a first value from a first lookup table using the engine speed data.
7. The method of claim 1 , wherein determining the torque offset includes retrieving a second value from a second lookup table using the engine speed data.
8. The method of claim 1 , further including summing the third measure with a torque-based frictional loss measure.
9. A method for estimating an output torque generated by a multi-displacement internal combustion engine operating in a partial-displacement mode, the engine including an intake manifold and an engine speed sensor generating engine speed data, the method comprising:
determining a first measure representing a mass air flow through the intake manifold based on a detected manifold air pressure and the engine speed data providing;
determining a mass-air-flow-to-torque conversion factor and a mass-air-flow-to-torque offset based on the engine speed data;
multiplying the first measure by the conversion factor to obtain a second measure representing a pre-offset base indicated torque;
summing the second measure with the torque offset to obtain a third measure representing a base indicated potential torque;
multiplying the base indicated potential torque measure with a torque-based efficiency conversion factor representing at least one of a spark efficiency measure, a fuel-air-ratio efficiency measure, and an exhaust gas recirculation efficiency measure, to obtain a third measure representing an efficiency-corrected indicated potential torque measure; and
summing the third measure with a torque-based frictional loss measure to obtain the estimated output torque.
10. The method of claim 9 , wherein the first measure represents a maximum mass air flow through the intake manifold, and wherein determining the first measure is further based on at least one of a barometric pressure, an inlet air temperature, an engine coolant temperature, and an exhaust gas oxygen content.
11. The method of claim 10 , wherein the first measure represents the maximum mass air flow through the intake manifold in a full-displacement engine operating mode, and wherein the first measure is further determined by multiplying the maximum mass air flow by a partial-displacement correction factor.
12. The method of claim 9 , further including calculating an average engine speed based on the engine speed data, and wherein determining the mass-air-flow-to-torque conversion factor is based on the average engine speed, and determining the torque offset is based on the average engine speed.
13. The method of claim 9 , wherein determining the mass-air-flow-to-torque conversion factor includes retrieving a first value from a first lookup table using the engine speed data.
14. The method of claim 9 , wherein determining the torque offset includes retrieving a second value from a second lookup table using the engine speed data.