Exhaust system component input pressure estimation systems and methods

1. A pressure determination system for a vehicle, comprising:

an output pressure module that sets an output pressure of a first component of an exhaust system of the vehicle equal to one of:

an input pressure of a second component that is immediately downstream of the first component in the exhaust system; and

ambient air pressure;

a pressure drop module that determines a pressure drop between an input of the first component and an output of the first component based a temperature of exhaust input to the first component;

an input pressure module that determines an input pressure of the first component based on a sum of the output pressure of the first component and the pressure drop between the input and the output of the first component; and

an actuator control module that selectively controls at least one engine actuator based on at least one of the input and output pressures of the first component.

2. The pressure determination system of claim 1 wherein:

the output pressure module further sets an output pressure of a third component of the exhaust system that is immediately upstream of the first component in the exhaust system equal to the input pressure of the first component;

the pressure drop module further determines a pressure drop between an input of the third component and an output of the third component based a temperature of exhaust input to the third component; and

the input pressure module further determines an input pressure of the third component based on a sum of the output pressure of the third component and the pressure drop between the input and the output of the third component.

3. The pressure determination system of claim 1 further comprising:

a viscosity module that determines a viscosity of the exhaust input to the first component based on the temperature of the exhaust input to the first component; and

a density module that determines a density of the exhaust input to the first component based on the temperature of the exhaust input to the first component,

wherein the pressure drop module determines the pressure drop between the input and the output of the first component based on the viscosity and the density of the exhaust input to the first component.

4. The pressure determination system of claim 3 further comprising:

an exhaust gas flowrate (EGF) determination module that determines an EGF through the first component; and

an EGF normalization module that determines a normalized EGF through the first component based on the EGF and the viscosity of the exhaust input to the first component,

wherein the pressure drop module determines the pressure drop between the input and the output of the first component based on the normalized EGF.

5. The pressure determination system of claim 4 further comprising:

a first normalization value module that determines a first normalization value for the first component based on the viscosity of the exhaust input to the first component and the density of the exhaust input to the first component,

wherein the pressure drop module further determines a normalized pressure drop between the input and the output of the first component based on the normalized EGF through the first component and determines the pressure drop between the input and the output of the first component based on the normalized pressure drop and the first normalization value.

6. The pressure determination system of claim 5 wherein the pressure drop module determines the pressure drop between the input and the output of the first component based on the normalized pressure drop divided by the first normalization value.

7. The pressure determination system of claim 5 wherein the first normalization value module determines the first normalization value for the first component based on the viscosity of the exhaust input to the first component, a normalized viscosity of the exhaust input to the first component, the density of the exhaust input to the first component, and a normalized density of the exhaust input to the first component.

8. The pressure determination system of claim 5 wherein the density module determines the density of the exhaust input to the first component further based on a normalized input pressure for the first component and determines the normalized input pressure for the first component based on a normalized ambient air pressure, a previous value of the input pressure of the first component, an ambient air pressure, and the first normalization value.

9. The pressure determination system of claim 4 further comprising:

a second normalization value module that determines a second normalization value for the first component based on the viscosity of the exhaust input to the first component,

wherein the EGF normalization module determines the normalized EGF through the first component based on the EGF through the first component and the second normalization value.

10. The pressure determination system of claim 9 wherein the second normalization value module determines the second normalization value for the first component based on the viscosity of the exhaust input to the first component and a normalized viscosity of the exhaust input to the first component.

11. A method for a vehicle, comprising:

setting an output pressure of a first component of an exhaust system of the vehicle equal to one of:

an input pressure of a second component that is immediately downstream of the first component in the exhaust system; and

ambient air pressure;

determining a pressure drop between an input of the first component and an output of the first component based a temperature of exhaust input to the first component;

determining an input pressure of the first component based on a sum of the output pressure of the first component and the pressure drop between the input and the output of the first component; and

selectively controlling at least one engine actuator based on at least one of the input and output pressures of the first component.

12. The method of claim 11 further comprising:

setting an output pressure of a third component of the exhaust system that is immediately upstream of the first component in the exhaust system equal to the input pressure of the first component;

determining a pressure drop between an input of the third component and an output of the third component based a temperature of exhaust input to the third component; and

determining an input pressure of the third component based on a sum of the output pressure of the third component and the pressure drop between the input and the output of the third component.

13. The method of claim 11 further comprising:

determining a viscosity of the exhaust input to the first component based on the temperature of the exhaust input to the first component;

determining a density of the exhaust input to the first component based on the temperature of the exhaust input to the first component; and

determining the pressure drop between the input and the output of the first component based on the viscosity and the density of the exhaust input to the first component.

14. The method of claim 13 further comprising:

determining an exhaust gas flowrate (EGF) through the first component;

determining a normalized EGF through the first component based on the EGF and the viscosity of the exhaust input to the first component; and

determining the pressure drop between the input and the output of the first component based on the normalized EGF.

15. The method of claim 14 further comprising:

determining a first normalization value for the first component based on the viscosity of the exhaust input to the first component and the density of the exhaust input to the first component;

determining a normalized pressure drop between the input and the output of the first component based on the normalized EGF through the first component; and

determining the pressure drop between the input and the output of the first component based on the normalized pressure drop and the first normalization value.

16. The method of claim 15 further comprising determining the pressure drop between the input and the output of the first component based on the normalized pressure drop divided by the first normalization value.

17. The method of claim 15 further comprising determining the first normalization value for the first component based on the viscosity of the exhaust input to the first component, a normalized viscosity of the exhaust input to the first component, the density of the exhaust input to the first component, and a normalized density of the exhaust input to the first component.

18. The method of claim 15 further comprising:

determining the density of the exhaust input to the first component further based on a normalized input pressure for the first component; and

determining the normalized input pressure for the first component based on a normalized ambient air pressure, a previous value of the input pressure of the first component, an ambient air pressure, and the first normalization value.

19. The method of claim 14 further comprising:

determining a second normalization value for the first component based on the viscosity of the exhaust input to the first component; and

determining the normalized EGF through the first component based on the EGF through the first component and the second normalization value.

20. The method of claim 19 further comprising determining the second normalization value for the first component based on the viscosity of the exhaust input to the first component and a normalized viscosity of the exhaust input to the first component.