SYSTEM AND METHODS FOR REDUCING VEHICLE EVAPORATIVE EMISSIONS

• US 20170198671A1
• Filed: 01/08/2016
• Published: 07/13/2017
• Est. Priority Date: 01/08/2016
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Dudar, Aed M.
• Granted Patent: US 9,856,830 B2
• Time in Patent Office: Days
• CPC Class Codes: B60K 6/20 the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs
• CPC Class Codes: F02D 2041/225 Leakage detection
• CPC Class Codes: F02D 2041/389 for injecting directly into the cylinder
• CPC Class Codes: F02D 2200/0602 Fuel pressure
• CPC Class Codes: F02D 41/0002 Controlling intake air
• CPC Class Codes: F02D 41/004 Control of the valve or purge actuator, e.g. duty cycle, closed loop control of position
• CPC Class Codes: F02D 41/042 for stopping the engine
• CPC Class Codes: F02D 41/221 relating to the failure of actuators or electrically driven elements
• CPC Class Codes: F02M 25/0854 Details of the absorption canister
• CPC Class Codes: F02M 25/089 Layout of the fuel vapour installation
• CPC Class Codes: F02M 26/13 Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
• CPC Class Codes: F02M 35/0218 acting by absorption or adsorption; trapping or removing vapours or liquids, e.g. originating from fuel
• CPC Class Codes: F02M 35/10019 Means upstream of the fuel injection system, carburettor or plenum chamber F02M35/10013 takes precedence
• CPC Class Codes: F02M 35/10222 Exhaust gas recirculation [EGR]; Positive crankcase ventilation [PCV]; Additional air admission, lubricant or fuel vapour admission
• CPC Class Codes: F02M 35/104 Intake manifolds
• CPC Class Codes: F02N 2019/008 the engine being stopped in a particular position

Abstract

Methods and systems are provided for reducing evaporative emissions in a vehicle during engine-off conditions responsive to an indication of undesired fuel outflow from one or more fuel injectors. In one example, at an engine-off event, an electric motor is operated to spin a vehicle engine unfueled to position a cylinder receiving fuel from a fuel injector with undesired fuel outflow with an intake valve open and an exhaust valve closed, and subsequently an onboard vacuum pump is activated to purge the contents of the cylinder to a fuel vapor canister. In this way, upon detection of undesired fuel outflow from one or more fuel injectors, during engine-off conditions mitigating action may be undertaken such that the undesired fuel outflow is purged to the fuel vapor canister, rather than being released as vapors to the environment.

Claims

1. A method comprising:

monitoring a fuel injector that supplies fuel to an engine cylinder having intake and exhaust valves; and

following an engine-off event and responsive to an undesired fuel outflow from the fuel injector;

positioning the intake valve and the exhaust valves to respective open and closed positions;

coupling the cylinder to a fuel vapor storage canister; and

purging fuel vapors from the undesired fuel outflow through the intake valve to the canister.

2. The method of claim 1, further comprising:

propelling a vehicle by either a combustion engine or an electric motor; and

wherein following an engine-off event, positioning the intake valve and the exhaust valve to respective open and closed positions includes spinning the combustion engine unfueled with the electric motor until the intake valve is open and the exhaust valve is closed.

3. The method of claim 2, further comprising:

selectively coupling an intake manifold of the combustion engine to atmosphere via a throttle;

selectively coupling the intake manifold of the combustion engine to the fuel vapor storage canister via a canister purge valve coupled within a purge line;

selectively coupling the fuel vapor storage canister to atmosphere via a canister vent valve coupled within a vent line;

selectively coupling a fuel tank to the fuel vapor storage canister via a fuel tank isolation valve; and

wherein coupling the cylinder to a fuel vapor storage canister includes closing the throttle, closing the fuel tank isolation valve, opening the canister purge valve, and opening the canister vent valve.

4. The method of claim 3, wherein a pump is positioned within the vent line, and wherein purging fuel vapors from the undesired fuel outflow includes activating the pump to apply vacuum on the cylinder that receives fuel from the fuel injector with undesired fuel outflow.

5. The method of claim 4, further comprising:

supplying pressurized fuel to a fuel rail fluidly coupled to a plurality of fuel injectors;

monitoring pressure in the fuel rail via a pressure sensor configured to indicate a fuel rail pressure; and

wherein monitoring a fuel injector includes indicating a fuel rail pressure decrease greater than a predetermined threshold, the fuel rail pressure decrease greater than the predetermined threshold indicating a fuel injector with undesired fuel outflow.

6. The method of claim 5, further comprising:

during purging fuel vapors from the undesired fuel outflow to the fuel vapor storage canister;

monitoring the fuel rail pressure; and

responsive to the fuel rail pressure reaching a second threshold;

coupling an exhaust manifold of the combustion engine to the fuel vapor storage canister; and

activating the pump to purge fuel vapors in exhaust manifold to the fuel vapor storage canister.

7. The method of claim 6, wherein coupling the exhaust manifold of the combustion engine to the fuel vapor canister includes positioning the cylinder with the intake valve and exhaust valve open by spinning the combustion engine unfueled.

8. The method of claim 6, further comprising:

selectively coupling an exhaust manifold to an intake manifold of the combustion engine via an exhaust gas recirculation valve coupled within an exhaust gas recirculation passage; and

wherein coupling the exhaust manifold of the combustion engine to the fuel vapor storage canister includes commanding open the exhaust gas recirculation valve.

9. The method of claim 6, further comprising:

during purging fuel vapors from the cylinder that receives fuel from the fuel injector with undesired fuel outflow and exhaust manifold to the fuel vapor storage canister;

monitoring temperature of the fuel vapor storage canister by a temperature sensor positioned within the fuel vapor storage canister near the vent line; and

responsive to an indication of a fuel vapor storage canister temperature increase above a threshold;

deactivating the pump;

closing the canister purge valve; and

spinning the combustion engine unfueled to close the intake valve and exhaust valve on the cylinder that receives fuel from the fuel injector with undesired fuel outflow.

10. The method of claim 9, further comprising:

during purging the exhaust manifold to the fuel vapor storage canister;

monitoring temperature of the fuel vapor storage canister by the temperature sensor positioned within the fuel vapor canister near the vent line; and

deactivating the pump and closing the canister purge valve responsive to a temperature plateau for a predetermined duration.

11. The method of claim 5, further comprising:

supplying pressurized fuel to the fuel rail at a key-on event; and

spinning the engine unfueled for a duration until a predetermined temperature is reached, the predetermined temperature comprising a temperature where liquid fuel trapped within an engine cylinder is likely to be vaporized.

12. A system for a vehicle, comprising:

an engine comprising one or more cylinders, each cylinder comprising an intake valve and an exhaust valve;

one or more fuel injectors, each supplying pressurized fuel to the one or more cylinders;

a fuel vapor canister coupled to an engine intake manifold via a canister purge valve;

a throttle coupled between the engine intake manifold and atmosphere;

a vacuum pump coupled between the fuel vapor canister and atmosphere; and

a controller configured with instructions stored in non-transitory memory, that when executed cause the controller to;

responsive to an indication of undesired fuel outflow from a fuel injector, following an engine-off event, position an engine cylinder receiving fuel from the fuel injector with undesired fuel outflow with the intake valve open and the exhaust valve closed;

close the throttle;

open the canister purge valve;

turn the vacuum pump on; and

purge fuel vapors from the engine cylinder to the fuel vapor canister.

13. The system of claim 12, further comprising:

an electric motor coupled to the engine; and

wherein

the controller is further configured with instructions stored in non-transitory memory, that when executed cause the controller to;

position the engine cylinder with the intake valve open and the exhaust valve closed by spinning the engine unfueled with the electric motor.

14. The system of claim 13, further comprising:

a temperature sensor coupled within the fuel vapor canister; and

wherein

the controller is further configured with instructions stored in non-transitory memory, that when executed cause the controller to;

during purging fuel vapors from the engine cylinder to the fuel vapor canister;

monitor fuel vapor canister temperature; and

responsive to a temperature increase above a threshold;

deactivate the vacuum pump;

close the canister purge valve; and

spin the engine unfueled to position the cylinder with intake valves and exhaust valves closed.

15. The system of claim 14, further comprising:

a fuel rail coupled to one or more fuel injectors;

a pressure sensor coupled to the fuel rail; and

wherein

the controller is further configured with instructions stored in non-transitory memory, that when executed cause the controller to;

monitor pressure in the fuel rail; and

indicate undesired fuel outflow from a fuel injector responsive to a fuel rail pressure decrease greater than a predetermined threshold.

16. The system of claim 15, wherein the controller is further configured with instructions stored in non-transitory memory, that when executed cause the controller to:

during purging fuel vapors from the engine cylinder to the fuel vapor canister;

monitor pressure in the fuel rail; and

responsive to a fuel rail pressure reaching a second threshold;

couple an exhaust manifold of the engine to the fuel vapor canister by spinning the engine unfueled to position the intake valve open and exhaust valve open;

activate the vacuum pump to purge fuel vapors from the exhaust manifold to the fuel vapor canister;

monitor temperature of the fuel vapor canister by the temperature sensor positioned within the fuel vapor canister; and

deactivate the vacuum pump and close the canister purge valve responsive to a temperature plateau for a predetermined duration.

17. The system of claim 16, further comprising:

an exhaust gas recirculation passage positioned between the intake manifold and the exhaust manifold;

an exhaust gas recirculation valve coupled within the exhaust gas recirculation passage; and

wherein

the controller is further configured with instructions stored in non-transitory memory, that when executed cause the controller to;

couple the exhaust manifold of the engine to the fuel vapor canister by commanding open the exhaust gas recirculation valve.

18. A method comprising:

propelling a vehicle by either a combustion engine or an electric motor;

monitoring a plurality of fuel injectors that supply pressurized fuel to a plurality of cylinders in the combustion engine; and

responsive to an indication of a fuel injector with undesired fuel outflow;

in a first condition, including an engine-on condition, adjust an air/fuel ratio to compensate for excess fuel in a cylinder receiving fuel from the fuel injector with undesired fuel outflow; and

in a second condition, including an engine-off condition, positioning the cylinder that receives fuel from the fuel injector with undesired fuel outflow with an intake valve open and an exhaust valve closed by spinning the engine unfueled via the electric motor;

coupling the cylinder to a fuel vapor canister, the fuel vapor canister configured to store vaporized hydrocarbons; and

activating a pump to purge fuel vapors resulting from undesired fuel outflow to the fuel vapor canister.

19. The method of claim 18, further comprising:

selectively coupling an intake manifold of the combustion engine to atmosphere via a throttle;

selectively coupling the intake manifold of the combustion engine to the fuel vapor canister via a canister purge valve coupled within a purge line;

selectively coupling the fuel vapor canister to atmosphere via a canister vent valve coupled within a vent line;

selectively coupling a fuel tank to the fuel vapor canister via a fuel tank isolation valve; and

wherein coupling the cylinder that receives fuel from the fuel injector with undesired fuel outflow to the fuel vapor canister includes closing the throttle, closing the fuel tank isolation valve, opening the canister purge valve, and opening the canister vent valve, and wherein activating the pump to purge fuel vapors resulting from undesired fuel outflow to the fuel vapor canister includes activating the pump to apply vacuum on the cylinder that receives fuel from the fuel injector with undesired fuel outflow.

20. The method of claim 19, further comprising:

during purging fuel vapor from the cylinder that receives fuel from the fuel injector with undesired fuel outflow to the fuel vapor canister;

monitoring temperature of the fuel vapor canister by a temperature sensor positioned within the fuel vapor canister near the vent line; and

responsive to an indication of a fuel vapor canister temperature increase above a threshold;

deactivating the pump;

closing the canister purge valve; and

spinning the combustion engine unfueled to close the intake valve and exhaust valve on the cylinder that receives fuel from the fuel injector with undesired fuel outflow.