Virtual compressor outlet temperature sensing for charge air cooler overheating protection

1. A method for controlling an internal combustion, compression-ignition engine, having an EGR circuit, a turbocharger compressor, and a charge air cooler, to avoid overheating the charge air cooler, the method comprising:

determining a crucial temperature above which damage to the charge air cooler could occur;

determining current ambient conditions;

determining current engine operating conditions;

processing an equation wherein a value of turbocharger compressor output temperature is predicted as a function of parameters representing the determined current ambient conditions and current engine operating conditions;

comparing the predicted turbocharger compressor output temperature with the determined crucial temperature; and

controlling the engine to prevent damage to the charge air cooler if the turbocharger compressor output temperature exceeds the determined crucial temperature.

2. The method as defined by claim 1 , wherein the step of determining a crucial temperature comprises assigning a value from a memory or storage of data.

3. The method as defined by claim 1 , wherein the step of determining current ambient conditions includes determining ambient air temperature and air pressure.

4. The method as defined by claim 1 , wherein the step of determining current engine operating conditions includes determining air mass flow rate and turbocharger compressor speed.

5. The method as defined by claim 1 , wherein the step of controlling the engine comprises reducing the temperature of the charge air cooler.

6. The method as defined by claim 5 , wherein reducing the temperature of the charge air cooler comprises bypassing at least a portion of the charge air around the charge air cooler before said portion of the charge air around the charge air cooler is directed to an intake manifold of the engine.

7. The method as defined by claim 1 , wherein the step of processing an equation comprises instructions for processing the following equation:

TCO

=

ATS

×

CF

η

TT

⁢

(

P

r

γ

-

1

γ

-

1

+

η

TT

)

where: ATS is the temperature of the turbocharger compressor inlet;

η TT is the compressor efficiency;

P r is the compressor pressure ratio;

γ is the ratio of specific heats; and

CF is the TCO sensor correction factor.

8. A computer-readable storage medium having stored data representing instructions executable by a computer to control an internal combustion, compression-ignition engine, having an EGR circuit, a charge air cooler, and a turbocharger compressor, to avoid overheating the charge air cooler, the computer-readable storage medium comprising:

instructions for determining a crucial temperature above which damage to the charge air cooler could occur;

instructions for determining current ambient conditions;

instructions for determining current engine operating conditions;

instructions for processing an equation wherein a value of turbocharger compressor output temperature is predicted as a function of parameters representing the determined current ambient conditions and current engine operating conditions;

instructions for comparing the predicted turbocharger compressor output temperature with the determined crucial temperature; and

instructions for controlling the engine to prevent damage to the charge air cooler if the turbocharger compressor output temperature exceeds the determined crucial temperature.

9. The computer-readable storage medium as defined by claim 8 , wherein the instructions for determining a crucial temperature include instructions for assigning a value from a memory or storage of data.

10. The computer-readable storage medium as defined by claim 8 , wherein the instructions for determining current ambient conditions include instructions for determining ambient air temperature and air pressure.

11. The computer-readable storage medium as defined by claim 8 , wherein the instructions for determining current engine operating conditions include instructions for determining air mass flow rate and turbocharger compressor speed.

12. The computer-readable storage medium as defined by claim 8 , wherein the instructions for controlling the engine comprise instructions for reducing the temperature of the charge air cooler.

13. The computer-readable storage medium as defined by claim 12 , wherein the instructions for reducing the temperature of the charge cooler comprise instructions for bypassing at least a portion of the charge air around the charge air cooler before said portion of the charge air around the charge air cooler is directed to an intake manifold of the engine.

14. The computer-readable storage medium as defined by claim 8 , wherein the instructions for processing an equation comprise instructions for processing the following equation:

TCO

=

ATS

×

CF

η

TT

⁢

(

P

r

γ

-

1

γ

-

1

+

η

TT

)

where: ATS is the temperature of the turbocharger compressor inlet;

η TT is the compressor efficiency;

P r is the compressor pressure ratio;

γ is the ratio of specific heats; and

CF is the TCO sensor correction factor.

15. A system for controlling an internal combustion, compression-ignition engine, having an EGR circuit, a turbocharger compressor, and a charge air cooler, to avoid overheating the charge air cooler, the system comprising:

a computer-readable storage medium storing a value of a crucial temperature above which damage to the charge air cooler could occur;

ambient condition sensors for determining current ambient conditions;

engine condition sensors for determining current engine operating conditions;

a charge air bypass valve for selectively bypassing at least a portion of charge air around the charge air cooler before it is combined with recirculated exhaust gas; and

a processor for calculating an equation wherein a value of turbocharger compressor output temperature is predicted as a function of parameters representing the determined current ambient air temperature, current air pressure, rotational speed of the turbocharger compressor, and air mass flow rate, the processor comparing the predicted turbocharger compressor output temperature with the determined crucial temperature, the charge air bypass valve being responsive to a processor command to bypass at least a portion of charge air around the charge air cooler if the predicted turbocharger compressor output temperature exceeds the determined crucial temperature.

16. The system as defined by claim 15 , wherein the ambient condition sensors comprise:

a temperature sensor for determining current ambient air temperature; and

a pressure sensor for determining current air pressure.

17. The system as defined by claim 15 , wherein the engine condition sensors comprise:

a turbo speed sensor for determining the rotational speed of the turbocharger compressor; and

an air mass flow rate sensor for determining air mass flow rate through the turbocharger compressor.

18. The system as defined by claim 15 , wherein the equation calculated by the processor comprises the following:

TCO

=

ATS

×

CF

η

TT

⁢

(

P

r

γ

-

1

γ

-

1

+

η

TT

)

where: ATS is the temperature of the turbocharger compressor inlet;

η TT is the compressor efficiency;

P r is the compressor pressure ratio;

γ is the ratio of specific heats; and

CF is the TCO sensor correction factor.