Method and apparatus for estimating exhaust pressure of an internal combustion engine
A method and apparatus are provided, comprising an internal combustion engine equipped with a variable geometry intake air compressing device and a control module operative to estimate exhaust gas pressure during ongoing engine operation. The control module is adapted to monitor sensing devices of the internal combustion engine, and is adapted to execute algorithms. The method comprises monitoring signal inputs from the sensing devices, and determining operating parameters for exhaust flow and an exhaust pressure of the intake air compressing device. An exhaust pressure ratio is determined based upon the parameters for exhaust flow and the exhaust pressure of the intake air compressing device. An exhaust pressure is determined based upon the exhaust pressure ratio.
1. Method to estimate an exhaust pressure of an internal combustion engine equipped with an intake air compressing device, comprising:
determining parameters for exhaust flow and opening of the intake air compressing device;
determining an exhaust pressure ratio based upon the exhaust flow and the opening of the intake air compressing device; and,
determining exhaust pressure based upon the exhaust pressure ratio.
2. The method of claim 1 , wherein determining the parameter for exhaust flow comprises determining a mass of exhaust flow corrected based upon a temperature of the exhaust and a pressure at a turbine outlet of the intake air compressing device.
3. The method of claim 1 , wherein determining the exhaust pressure based upon the exhaust pressure ratio further comprises determining the exhaust pressure based upon a pressure at a turbine outlet of the intake air compressing device.
4. The method of claim 1 , further comprising determining a rotational speed of the intake air compressing device; and, determining the exhaust pressure ratio based upon the exhaust flow, the exhaust pressure of the intake air compressing device, and the rotational speed of the intake air compressing device.
5. The method of claim 1 , wherein determining the exhaust pressure ratio based upon the exhaust flow and the opening of the intake air compressing device comprises determining the exhaust pressure ratio based upon a predetermined calibration map.
6. The method of claim 1 , wherein determining the exhaust pressure ratio based upon the exhaust flow and the opening of the intake air compressing device comprises calculating the exhaust pressure ratio with a second-order polynomial equation.
7. Powertrain, comprising:
an internal combustion engine equipped with a variable geometry intake air compressing device; and,
a control module:
adapted to monitor a plurality of sensing devices of the internal combustion engine and control a plurality of actuators; and,
adapted to execute a plurality of algorithms contained therein to effect the following, the algorithms comprising:
i) code to determine parameters for exhaust flow and opening of the intake air compressing device;
ii) code to determine an exhaust pressure ratio based upon the exhaust flow and the opening of the intake air compressing device; and
iii) code to determine an exhaust pressure based upon the exhaust pressure ratio.
8. The powertrain of claim 7 , wherein the control module adapted to execute code to determine an exhaust pressure ratio based upon the exhaust flow and opening of the intake air compressing device comprises code to determine the exhaust pressure ratio based upon a plurality of selectively retrievable predetermined parameters for exhaust pressure ratio stored in tabular format.
9. The powertrain of claim 7 , wherein the control module adapted to execute code to determine an exhaust pressure ratio based upon the exhaust flow and the exhaust pressure of the intake air compressing device comprises code to execute a polynomial equation.
10. The powertrain of claim 7 , wherein the code to determine the exhaust pressure ratio based upon the exhaust flow further comprises code to correct the exhaust flow based upon an outlet pressure of the intake air compressing device, and engine exhaust gas temperature.
11. The powertrain of claim 7 , wherein the code to determine the exhaust pressure based upon the exhaust pressure ratio comprises code to mathematically multiply the exhaust pressure ratio by an outlet pressure of the intake air compressing device.
12. The powertrain of claim 7 , wherein the internal combustion engine comprises a compression-ignition engine.
13. The powertrain of claim 7 , wherein the internal combustion engine comprises a homogeneous charge compression-ignition engine.
14. The powertrain of claim 7 , wherein the internal combustion engine comprises a spark-ignition engine.