Method of determining air charging system deficient state of health during part load operation
A method to diagnose post air charger compressor icing obstructions without the addition of a post compressor pressure sensor. The method detects when conditions exists for icing to occur and performs at least one icing mitigation strategy when the icing conditions exceed a predetermined icing condition threshold.
1. A method of determining an air charger system deficient state of health condition during engine part load operation comprising:
an engine;
an intake line;
a compressor positioned in the intake line and configured to provide compressed air to the engine;
a charge air cooler provided in the intake line downstream of the compressor and upstream of the engine;
a charge air cooler pressure sensor; and
a controller, wherein the controller is configured to perform the steps of:
detecting if the engine is operating at a steady state condition;
detecting if the air charger system deficient state of health condition exists when the engine is operating at a steady state condition;
calculating a charge air cooler pressure based on engine speed, intake manifold pressure and barometric pressure when the air charger deficient state of health condition exists;
measuring a charge air cooler pressure of the charge air cooler via the charge air cooler sensor;
comparing the calculated charge air cooler pressure to the measured charge air cooler pressure;
starting a deficient state of health condition timer when a difference between the calculated charge air cooler pressure and the measured charge air cooler pressure is greater than a predetermined charge air cooler pressure difference threshold; and
performing at least one mitigation strategy when the deficient state of health condition timer indicates that a period of time has elapsed which is greater than a predetermined timer threshold.
2. The method of claim 1 wherein the air charger system deficient state of health condition is caused by icing.
3. The method of claim 1 wherein detecting the air charger system deficient state of health condition further comprises detecting that a positive crankcase ventilation gas flows into the intake line via a positive crankcase ventilation line.
4. The method of claim 3 wherein the positive crankcase ventilation pas flows into the intake line via the positive crankcase ventilation line when engine manifold air pressure (MAP) is greater than a predetermined MAP pressure threshold.
5. The method of claim 4 wherein the positive crankcase ventilation line comprises a valve to selectively admit positive crankcase ventilation gas into the intake line.
6. The method of claim 1 wherein the step of calculating the charge air cooler pressure is further based on an outlet air pressure of the compressor.
7. The method of claim 1 wherein the step of calculating the charge air cooler pressure is further based on the engine speed from a crankshaft position sensor signal.
8. The method of claim 1 wherein the step of calculating the charge air cooler pressure is further based on the intake manifold pressure from a MAP sensor signal.
9. The method of claim 1 wherein the step of calculating the charge air cooler pressure is further based on the barometric pressure from a barometric sensor signal.
10. The method of claim 1 wherein the step of performing the at least one mitigation strategy further comprises changing a current gear state to a lower gear state.
11. The method of claim 10 wherein the step of changing the current gear to the lower gear state further comprises reducing a throttle body opening.
12. The method of claim 4 wherein the air charger system deficient state of health condition is caused by icing.
13. The method of claim 4 wherein the positive crankcase ventilation line comprises a valve to selectively admit positive crankcase ventilation gas into the intake line.
14. The method of claim 4 wherein the step of calculating the charge air cooler pressure is based on an outlet air pressure of the compressor.
15. The method of claim 4 wherein the step of performing the at least one mitigation strategy further comprises changing a current gear state to a lower gear state.
16. The method of claim 4 wherein the step of changing the current gear state to the lower gear state further comprises reducing a throttle body opening.
17. The method of claim 4 wherein the step of calculating the charge air cooler pressure is further based on the barometric pressure from a barometric sensor signal.
18. The method of claim 4 wherein the step of calculating the charge air cooler pressure is further based on the engine speed from a crankshaft position sensor signal.
19. A system comprising:
an engine;
an intake line;
a compressor positioned in the intake line and configured to provide compressed air to the engine;
a charge air cooler provided in the intake line downstream of the compressor and upstream of the engine;
a charge air cooler pressure sensor; and
a controller, wherein the controller is configured to perform the steps of:
detecting if the engine is operating at a steady state condition;
detecting if an air charger system deficient state of health condition exists when the engine is operating at a steady state condition;
calculating a charge air cooler pressure based on engine speed, intake manifold pressure and barometric pressure when the air charger deficient state of health condition exists;
measuring a charge air cooler pressure of the charge air cooler via the charge air cooler sensor;
comparing the calculated charge air cooler pressure to the measured charge air cooler pressure;
starting a deficient state of health condition timer when a difference between the calculated charge air cooler pressure and the measured charge air cooler pressure is greater than a predetermined charge air cooler pressure difference threshold; and
performing at least one mitigation strategy when the deficient state of health condition timer indicates that a period of time has elapsed which is greater than a predetermined timer threshold.