Method for estimating charge air cooler condensation storage with an intake oxygen sensor while exhaust gas recirculation is flowing

Patent metadata

Field	Value
Publication number	US-9416740-B2
Application number	US-201414192765-A
Country	US
Kind code	B2
Filing date	Feb 27, 2014
Priority date	Feb 27, 2014
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

Methods and systems are provided for estimating water storage in a charge air cooler (CAC). In one example, an amount of water accumulating in the CAC may be based on an output of an oxygen sensor positioned downstream of the CAC, ambient humidity, and EGR flow while EGR is flowing. Additionally, engine actuators may be adjusted to purge condensate from the CAC and/or reduce condensate formation based on the amount of water inside the CAC.

First claim

The invention claimed is:

1. An engine method, comprising:
adjusting engine actuators based on one or more of a water storage amount and water storage rate at a charge air cooler (CAC), the one or more of the water storage amount and water storage rate determined based on an output of an oxygen sensor positioned downstream of the CAC, ambient humidity, and a determined amount of exhaust gas recirculation (EGR) flow.

2. The method of claim 1 , wherein the determined amount of EGR flow is a non-zero amount of EGR flow, the determined amount based on an output of an EGR flow sensor positioned in a low-pressure EGR passage positioned between an exhaust passage downstream from a turbine and an intake passage upstream of a compressor while EGR is flowing at a desired EGR flow amount determined based on operating conditions of the engine.

3. The method of claim 2 , wherein the EGR flow sensor is a differential pressure over valve (DPOV) sensor and wherein the EGR flow is estimated based on an output of the DPOV sensor, an EGR temperature, and an area of EGR valve opening detected by an EGR valve lift sensor.

4. The method of claim 2 , wherein the ambient humidity is measured by a humidity sensor positioned in the intake passage upstream of the CAC and an outlet from the low-pressure EGR passage and into the intake passage.

5. The method of claim 2 , wherein the one or more of the water storage amount and water storage rate is based on a difference between a water content of charge air entering the CAC and a water content of the charge air exiting the CAC, the water content of the charge air entering the CAC based on the ambient humidity and the EGR flow while EGR is flowing through the low-pressure EGR passage and the water content of the charge air exiting the CAC based on the output of the oxygen sensor.

6. The method of claim 1 , wherein the water storage amount is one of an amount of water stored within the CAC and the water storage rate is a water accumulation rate within the CAC.

7. The method of claim 6 , wherein adjusting engine actuators based on the one or more of the water storage amount and water storage rate includes adjusting one or more of vehicle grille shutters, engine cooling fans, or a CAC coolant pump to decrease a cooling efficiency of the CAC in response to the water storage rate increasing above a threshold rate and wherein adjusting engine actuators based on the one or more of the water storage amount and water storage rate includes decreasing an opening of an EGR valve positioned in a low-pressure EGR passage responsive to the water storage rate increasing above the threshold rate.

8. The method of claim 6 , wherein adjusting engine actuators based on the one or more of the water storage amount and water storage rate includes increasing engine airflow to purge condensate from the CAC in response to the amount of water stored within the CAC increasing above a threshold amount.

9. The method of claim 1 , wherein the oxygen sensor is an intake oxygen sensor positioned at an outlet of the CAC.

10. The method of claim 1 , wherein ambient humidity is estimated based on one or more of intake temperature, intake pressure, and a windshield wiper duty cycle.

11. The method of claim 1 , wherein ambient humidity is determined based on weather data received from one or more of a weather station, remote device, or in-vehicle entertainment and communications system.

12. An engine method, comprising:
adjusting engine actuators based on a water storage rate at a charge air cooler (CAC), the water storage rate based on an output of an oxygen sensor positioned downstream of the CAC, a humidity measurement, and an exhaust gas recirculation (EGR) flow measurement during a first condition when EGR is flowing and the water storage rate based on the output of the oxygen sensor and the humidity measurement during a second condition when EGR is not flowing.

13. The method of claim 12 , wherein the water storage rate is based on a difference between water entering the CAC and water exiting the CAC, the water entering the CAC based on the humidity measurement and the EGR flow measurement and the water exiting the CAC based on the output of the oxygen sensor.

14. The method of claim 12 , wherein adjusting engine actuators includes adjusting one or more of spark timing or mass air flow in response to the water storage rate being negative.

15. The method of claim 14 , wherein adjusting spark timing includes retarding spark timing when a pedal position is increasing and advancing spark timing when the pedal position is below a threshold position.

16. The method of claim 12 , wherein adjusting engine actuators includes adjusting one or more of vehicle grille shutters, engine cooling fans, CAC cooling fans, or a CAC coolant pump to decrease cooling efficiency of the CAC in response to the water storage rate increasing above a threshold rate.

17. The method of claim 12 , further comprising estimating a water storage amount based on the water storage rate and wherein adjusting engine actuators includes increasing engine airflow to purge water from the CAC in response to the water storage amount increasing above a threshold amount.

18. The method of claim 12 , wherein the EGR flow measurement is one or more of low-pressure or high-pressure EGR where EGR is injected via an EGR outlet into an intake passage upstream of the CAC and wherein the humidity measurement is measured by a humidity sensor positioned upstream of the CAC and upstream of the EGR outlet.

19. An engine system, comprising:
an intake manifold;
a charge air cooler positioned upstream of the intake manifold in an intake passage;
an oxygen sensor positioned at an outlet of the charge air cooler;
a low-pressure exhaust gas recirculation (EGR) passage coupled between an exhaust passage downstream of a turbine and the intake passage upstream of a compressor, the low-pressure EGR passage including a low-pressure EGR valve and low-pressure DPOV sensor for measuring low-pressure EGR flow;
a humidity sensor positioned in the intake passage upstream of the low-pressure EGR passage; and
a controller with computer readable instructions for adjusting engine operation responsive to a water storage rate at the charge air cooler, the water storage rate based on an output of the oxygen sensor, an output of the humidity sensor, and the measured low-pressure EGR flow when low-pressure EGR is flowing.

20. The system of claim 19 , further comprising a high-pressure EGR system coupled between the exhaust passage upstream of the turbine and the intake passage downstream of the compressor and upstream of the charge air cooler, the high-pressure EGR system including a high-pressure EGR valve and high-pressure DPOV sensor for measuring high-pressure EGR flow and wherein the water storage rate is further based on the measured high-pressure EGR flow when high-pressure EGR is flowing.

Assignees

• Ford Global Tech Llc

Inventors

• Styles Daniel Joseph
• Surnilla Gopichandra
• Hilditch James Alfred

Classifications

• F02D2041/0075

  by using flow sensors · CPC title

• F02D2200/0418

  Air humidity · CPC title

• Y02T10/144

  Cross-Sectional Technologies · mapped topic

• F02D41/0025

  Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures · CPC title

• F02D41/144

  Sensor in intake manifold · CPC title