Methods and systems for removing moisture from engine exhaust system

Patent metadata

Field	Value
Publication number	US-10598060-B2
Application number	US-201815902946-A
Country	US
Kind code	B2
Filing date	Feb 22, 2018
Priority date	Feb 22, 2018
Publication date	Mar 24, 2020
Grant date	Mar 24, 2020

Abstract

Methods and systems are provided for removing moisture from an engine exhaust system. In one example, a method includes, during a vehicle key-off condition, in response to a higher than threshold exhaust moisture level and a lower than threshold engine run time during an immediately prior drive cycle, operating an electric air compressor to remove the moisture accumulated in the exhaust manifold.

First claim

The invention claimed is:

1. A method comprising:
estimating a moisture level in at least one of an exhaust system and an intake system based on input from one or more of on-board cameras and a humidity sensor, and, responsive to each of a run-time of an engine of a vehicle during a drive cycle being below a threshold duration and the moisture level in one of the exhaust system and the intake system being higher than a threshold level, at a key-off event following the drive cycle, activating, via an electronic controller, an electric air compressor in the intake system to expel moisture from at least the exhaust system.

2. The method of claim 1 , wherein activating the electric air compressor is further based on a lower than threshold exhaust temperature during the drive cycle.

3. The method of claim 1 , wherein the moisture level is estimated via on-board cameras configured to determine an amount of moisture on a windshield of the vehicle during a previous key-off event.

4. The method of claim 3 , wherein the drive cycle is immediately prior to the key-off event, and the previous key-off event is immediately prior to the drive cycle.

5. The method of claim 3 , wherein the moisture level is further estimated as a function of ambient humidity at a location of the vehicle during the previous key-off event.

6. The method of claim 1 , wherein the run-time of the engine is a function of a number of start-stop events, a duration of each start-stop event, a number of deceleration fuel shut-off (DFSO) events, and a duration of each DFSO event during the drive cycle.

7. The method of claim 1 , wherein expelling the moisture from at least the exhaust system includes routing compressed air from the electric air compressor through the intake system and the exhaust system to remove moisture from each of the intake system and the exhaust system to atmosphere.

8. The method of claim 1 , wherein the electric air compressor is coupled to a conduit parallel to an intake passage, the conduit coupled to the intake passage downstream of an intake compressor and upstream of a charge air cooler, the method further comprising closing an electric air compressor bypass valve coupled to the intake passage, downstream of the intake compressor, to direct ambient air into the conduit.

9. The method of claim 1 , wherein the engine includes an exhaust gas recirculation passage coupling the exhaust system to the intake system, downstream of the electric air compressor, and wherein routing the compressed air through the intake system and the exhaust system further includes opening an exhaust gas recirculation (EGR) valve coupled to the exhaust gas recirculation passage to flow compressed air exiting the electric air compressor to the exhaust system.

10. The method of claim 9 , further comprising, while opening the EGR valve, actuating an intake throttle coupled to an intake passage downstream of a charge air cooler to a wide open position, and actuating a wastegate valve positioned in a wastegate passage which is coupled in parallel to a turbine positioned in the exhaust system, to route compressed air from the electric air compressor into the exhaust system.

11. The method of claim 5 , wherein the ambient humidity is measured via one or more of an intake humidity sensor, a windshield humidity sensor, or inferred based on weather data including ambient humidity conditions retrieved from an external network communicatively coupled to the vehicle via wireless communication.

12. A method, comprising:
at an onset of a drive cycle of a vehicle, estimating a first moisture level in an exhaust system of an engine;
at a completion of the drive cycle, estimating a second moisture level in the exhaust system based on the first moisture level; and
during an immediately subsequent vehicle key-off condition, responsive to the second moisture level being higher than a threshold level, activating, via an electronic controller, an air compressor to route compressed air from an engine intake manifold through the exhaust system,
wherein the first moisture level is estimated based on one or more of an amount of moisture accumulated on a windshield of the vehicle during an immediately previous vehicle key-off condition, a variation in ambient humidity during the immediately previous vehicle key-off condition, and a dew point temperature at a location of the vehicle during the immediately previous vehicle key-off condition.

13. The method of claim 12 , wherein the second moisture level is further based on a duration of operation of the engine during the drive cycle and a temperature of an exhaust manifold during the drive cycle.

14. The method of claim 12 , wherein the activating the air compressor includes operating an electric air compressor coupled to the engine intake manifold to flow compressed air from the engine intake manifold to the exhaust system.

15. The method of claim 12 , wherein routing compressed air further includes opening a throttle coupled to the engine intake manifold, opening an exhaust gas recirculation (EGR) valve housed in an EGR passage coupling the engine intake manifold to an exhaust manifold of the exhaust system, and opening a wastegate valve housed in a wastegate passage coupled to the exhaust manifold across a turbine.

16. The method of claim 14 , wherein operating the electric air compressor includes operating the electric air compressor for a duration based on a difference between the second moisture level and the threshold level, the duration increased with an increase in the difference.

17. A system, comprising:
a vehicle, including an autonomous vehicle and/or a hybrid vehicle;
an electric machine coupled to a battery for propelling the vehicle;
an engine including one or more cylinders, an intake manifold, and an exhaust manifold;
an intake passage including a compressor, a charge air cooler (CAC) downstream of the compressor, and an intake throttle downstream of the CAC;
a conduit coupled to the intake passage downstream of the compressor and upstream of the CAC, the conduit including a motor-driven electric compressor;
an electric compressor bypass valve coupled at a junction of the intake passage and the conduit;
one or more sensors including each of an ambient humidity sensor coupled to the intake manifold and an exhaust temperature sensor coupled to the exhaust manifold;
one or more cameras to capture images of a windshield;
an exhaust gas recirculation (EGR) passage coupling the exhaust manifold to the intake manifold, downstream of the compressor, the EGR passage including an EGR valve; and
a controller with computer readable instructions stored on non-transitory memory to:
estimate a moisture level in the exhaust manifold at an end of a drive cycle based on one or more images of the windshield, an ambient humidity as estimated via the ambient humidity sensor, a duration of engine operation, and a variation in exhaust temperature during the drive cycle; and
in response to a higher than threshold moisture level, during an immediately subsequent vehicle key-off condition, operate the electric compressor to route compressed air through the exhaust manifold to remove moisture from the exhaust manifold.

18. The system of claim 17 , wherein the one or more images of the windshield are captured during a vehicle key-off event immediately prior to the drive cycle and wherein the ambient humidity is monitored over a duration of the vehicle key-off event immediately prior to the drive cycle.

19. The system of claim 17 , wherein the duration of engin

Assignees

• Ford Global Tech Llc

Inventors

• Dudar Aed

Classifications

• F01N3/323

  Electrically driven air pumps · CPC title

• F01N2900/12

  said parameters being related to the vehicle exterior · CPC title

• F02D2200/60

  said parameters being related to the driver demands or status · CPC title

• F01N9/00

  Electrical control of exhaust gas treating apparatus (monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00) · CPC title

• F02D41/0077

  Control of the EGR valve or actuator, e.g. duty cycle, closed loop control of position (EGR valve position sensor F02M26/48) · CPC title