Method for dynamic mass air flow sensor measurement corrections
View Patent ↗A mass airflow sensor measurement correction system for a turbocharged diesel engine operating under transient conditions includes a signal input device that generates an engine speed signal based on an engine speed of a turbocharged diesel engine. A control module receives the engine speed signal and calculates a correction value of mass airflow from a differential of the engine speed signal and a constant.
1. A mass airflow sensor measurement correction system for a turbocharged diesel engine operating under transient conditions, comprising:
a engine speed signal input device that receives an engine speed signal based on an engine speed of a turbocharged diesel engine; and
a control module that receives said engine speed signal and that calculates a correction value of mass airflow from a differential of said engine speed signal and a first constant and that applies said correction value to a measured mass airflow value.
2. The system of claim 1 wherein said first constant is determined from at least one of a displacement volume of said engine, a volumetric efficiency of said engine, a temperature of an intake manifold, and a gas constant.
3. The system of claim 2 wherein said first constant is adjusted based on delays of said signal input device and delays of said control module processing.
4. The system of claim 1 wherein said control module determines said differential of said engine speed signal and calculates said correction value from said first constant and said differential according to the following equation:
ⅆ
MAF
ⅆ
t
=
K
1
ⅆ
RPM
ⅆ
t
.
5. The system of claim 1 further comprising a manifold absolute pressure signal input device that receives a manifold absolute pressure signal based on a pressure of an intake manifold coupled to said engine, and wherein said control module is receptive of said manifold absolute pressure signal and is operable to calculate a correction value of mass airflow from said engine speed signal, said manifold absolute pressure signal, and said first constant.
6. The system of claim 5 wherein said control module determines a differential of said engine speed signal, determines a differential of said manifold absolute pressure signal and calculates said correction value based on said engine speed signal, said manifold absolute pressure signal, said differential of said engine speed signal, said differential of said manifold absolute pressure signal, and said first constant according to the following equation:
ⅆ
MAF
ⅆ
t
=
K
1
[
RPM
(
ⅆ
MAP
ⅆ
t
)
+
MAP
(
ⅆ
RPM
ⅆ
t
)
]
.
7. The system of claim 5 wherein said control module determines a differential of said engine speed signal, determines a differential of said manifold absolute pressure signal, and calculates said correction value based on said differential of said engine speed, said differential of said manifold absolute pressure signal, said first constant, and a second constant according to the following equation:
ⅆ
MAF
ⅆ
t
=
K
1
ⅆ
RPM
ⅆ
t
+
K
2
ⅆ
MAP
ⅆ
t
.
8. The system of claim 7 wherein said second constant is determined from at least one of a displacement volume of said engine, a volumetric efficiency of said engine, a temperature of an intake manifold, and a gas constant.
9. The system of claim 8 wherein said second constant is adjusted based on delays of said signal input device and delays of control module processing.
10. The system of claim 1 further comprising a manifold absolute pressure signal input device that receives a manifold absolute pressure signal based on an air pressure of an intake manifold, and wherein said control module is receptive of said manifold absolute pressure signal and is operable to calculate said correction value of mass airflow from said manifold absolute pressure signal and said first constant.
11. The system of claim 10 wherein said control module determines a differential of said manifold absolute pressure signal and calculates said correction value based on said differential of said manifold absolute pressure signal and said first constant according to the following equation:
ⅆ
MAF
ⅆ
t
=
K
1
ⅆ
MAP
ⅆ
t
.
12. The system of claim 1 wherein said control module determines a mass airflow per cylinder value from said correction value.
13. The system of claim 12 wherein said control module controls a fuel injector of said engine based on said mass airflow per cylinder value.
14. A method of correcting a mass airflow sensor measurement of an engine operating under transient conditions, comprising:
detecting a speed of an engine;
determining a first differential of said speed of said engine; and
calculating a value for a mass airflow sensor measurement based on said first differential of said speed and a first constant.
15. The method of claim 14 further comprising selecting a first constant based on at least one of a displacement volume of said engine, a volumetric efficiency of said engine, a temperature of an intake manifold, and a gas constant.
16. The method of claim 14 wherein said step of calculating is based on the following equation:
ⅆ
MAF
ⅆ
t
=
K
1
ⅆ
RPM
ⅆ
t
.
17. The method of claim 14 further comprising:
detecting an air pressure form an intake manifold of said engine;
determining a second differential of said air pressure of said manifold; and
wherein said step of calculating is further described as calculating a correction value based on said first differential of said speed, said first constant, said second differential of said air pressure, and a second constant.
18. The method of claim 17 wherein said step of calculating is based on the following equation:
ⅆ
MAF
ⅆ
t
=
K
1
ⅆ
RPM
ⅆ
t
+
K
2
ⅆ
MAP
ⅆ
t
.
19. The method of claim 17 further comprising selecting a second constant based on at least one of a displacement volume of said engine, a volumetric efficiency of said engine, a temperature of an intake manifold, and a gas constant.
20. The method of claim 17 wherein said step of calculating is further described as calculating a correction value based on said speed of said engine, said first differential of said speed, said first constant, said air pressure, and said second differential of said air pressure.
21. The method of claim 20 wherein said step of calculating is based on the following equation:
ⅆ
MAF
ⅆ
t
=
K
1
[
RPM
(
ⅆ
MAP
ⅆ
t
)
+
MAP
(
ⅆ
RPM
ⅆ
t
)
]
.
22. The method of claim 14 further comprising calculating a mass airflow per cylinder value based on said correction value.
23. The method of claim 22 further comprising controlling fuel of said engine based on said mass airflow per cylinder value.
24. The method of claim 22 further comprising controlling an exhaust gas recirculation system of said engine based on said mass airflow per cylinder value.
25. The method of claim 22 further comprising controlling a smoke control system based on said mass airflow per cylinder value.
26. A method of correcting a mass air flow sensor measurement of an engine system with an intake manifold, comprising:
detecting an air pressure of a manifold;
determining a first differential of said air pressure; and
calculating a correction value for a mass airflow sensor measurement based on said first differential of said air pressure and a first constant.
27. The method of claim 26 further comprising selecting a first constant based on at least one of a displacement volume of said engine, a volumetric efficiency of said engine, a temperature of an intake manifold, and a gas constant.
28. The method of claim 26 wherein said step of calculating is based on the following equation:
ⅆ
MAF
ⅆ
t
=
K
1
ⅆ
MAF
ⅆ
t
.
29. The method of claim 26 further comprising calculating a mass airflow per cylinder value based on said correction value.
30. The method of claim 29 further comprising controlling fuel of said engine based on said mass airflow per cylinder value.
31. The method of claim 29 further comprising controlling an exhaust gas recirculation system based on said mass airflow per cylinder value.
32. The method of claim 29 further comprising controlling a smoke control system based on said mass airflow per cylinder value.