Method for determining the exhaust pressure of a turbocharged internal combustion engine
A method for determining the exhaust pressure (P r ) of a turbocharged internal combustion engine, including a solenoid by-pass valve for the exhaust gas, characterized in that an exhaust pressure (P i ) is determined as a function of the inlet air flow to the engine, (A r ), the engine speed (R r ) and the degree of opening of the solenoid exhaust by-pass valve (T r ), by interpolation from a reference map having exhaust gas pressure values (P c ) for given inlet air flow values (A c ), the engine speed (R c ) and the degree of opening of the solenoid exhaust by-pass valve (T c ), and the exhaust pressure determined by the interpolation (P i ) is corrected as a function of ambient pressure values (P a , P o ).
1. A method of determining the exhaust pressure (P r ) of a turbocharged internal combustion engine comprising a wastegate, characterized in that
an exhaust pressure (P i ) is determined, as a function of the engine intake air flow rate (A r ), of the engine speed (R r ) and of the degree of wastegate opening (T r ), by an interpolation from a reference map comprising exhaust pressure values (P c ) for defined values of the intake air flow rate (A c ), of the engine speed (R c ) and of the degree of wastegate opening (T c ),
the exhaust pressure determined by the interpolation (P i ) is corrected, as a function of the ambient pressure prevailing during the determination of the exhaust pressure (P a ) and of the ambient pressure prevailing during the production of the map (P o ), according to the formula which follows:
P
r
=
P
i
(
P
i
(
1
-
P
a
P
o
K
-
P
a
)
+
K
P
a
P
o
-
P
a
K
-
P
a
)
in which P r is the corrected exhaust pressure, P i is the exhaust pressure determined by the interpolation, P o is the ambient pressure prevailing during the production of the map, P a is the ambient pressure prevailing during the determination of the exhaust pressure, and K is a corrective factor which is specific to the type of engine for which the map was produced and which is predetermined on a test bench by calibrating measurements at different ambient pressures.
2. The method as claimed in claim 1 , characterized in that the interpolation used is a linear interpolation.
3. The method as claimed in claim 1 , characterized in that the degree of wastegate opening (T c ) is represented by the actual position of the wastegate measured by a sensor.
4. The method as claimed in claim 1 , characterized in that the degree of wastegate opening (T c ) is represented by the value of the wastegate control.
5. The method as claimed in claim 4 , characterized in that the wastegate control is the applied control less the adaptation corrections.
6. A method of regulating a turbocharged internal combustion engine as a function of the exhaust pressure, characterized in that the exhaust pressure is determined as claimed in claim 1 .
7. The method as claimed in claim 2 , characterized in that the degree of wastegate opening (T c ) is represented by the actual position of the wastegate measured by a sensor.
8. The method as claimed in claim 2 , characterized in that the degree of wastegate opening (T c ) is represented by the value of the wastegate control.
9. The method as claimed in claim 3 , characterized in that the degree of wastegate opening (T c ) is represented by the value of the wastegate control.
10. A method of regulating a turbocharged internal combustion engine as a function of the exhaust pressure, characterized in that the exhaust pressure is determined as claimed in claim 2 .
11. A method of regulating a turbocharged internal combustion engine as a function of the exhaust pressure, characterized in that the exhaust pressure is determined as claimed in claim 3 .
12. A method of regulating a turbocharged internal combustion engine as a function of the exhaust pressure, characterized in that the exhaust pressure is determined as claimed in claim 4 .
13. A method of regulating a turbocharged internal combustion engine as a function of the exhaust pressure, characterized in that the exhaust pressure is determined as claimed in claim 5 .