System and methods for reducing vehicle evaporative emissions
First Claim
1. A method for a vehicle, comprising:
- monitoring a fuel injector that supplies fuel to cylinder of an engine, the 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 valve to respective open and closed positions;
coupling the cylinder to a fuel vapor storage canister;
purging fuel vapors from the undesired fuel outflow through the intake valve to the canister; and
during the purging fuel vapors from the undesired fuel outflow through the intake valve to the canister, monitoring a pressure in a fuel rail coupled to a plurality of fuel injectors, and, responsive to fuel rail pressure reaching a fuel rail pressure threshold, coupling an exhaust manifold of the engine to the canister to purge fuel vapors in the exhaust manifold to the canister.
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Accused Products
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.
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Citations
19 Claims
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1. A method for a vehicle, comprising:
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monitoring a fuel injector that supplies fuel to cylinder of an engine, the 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 valve to respective open and closed positions; coupling the cylinder to a fuel vapor storage canister; purging fuel vapors from the undesired fuel outflow through the intake valve to the canister; and during the purging fuel vapors from the undesired fuel outflow through the intake valve to the canister, monitoring a pressure in a fuel rail coupled to a plurality of fuel injectors, and, responsive to fuel rail pressure reaching a fuel rail pressure threshold, coupling an exhaust manifold of the engine to the canister to purge fuel vapors in the exhaust manifold to the canister. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for a vehicle, comprising:
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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; a temperature sensor coupled within the fuel vapor canister; 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 and 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; purge fuel vapors from the engine cylinder to the fuel vapor canister; monitor a temperature of the fuel vapor canister via the temperature sensor; and responsive to a temperature increase above a threshold, deactivate the vacuum pump and close the canister purge valve. - View Dependent Claims (12, 13, 14, 15)
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16. A method comprising:
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propelling a vehicle by either a engine or an electric motor; monitoring a plurality of fuel injectors that supply pressurized fuel from a fuel rail to a plurality of cylinders in the 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; activating a pump to purge fuel vapors resulting from undesired fuel outflow to the fuel vapor canister until a pressure in the fuel rail is below a threshold pressure, and then purging fuel vapors from an exhaust manifold of the engine to the fuel vapor storage canister, responsive to an indication that a fuel vapor storage canister load is not greater than a threshold load during the purging fuel vapors from the cylinder and/or from the exhaust manifold, wherein the canister load is indicated via a temperature sensor positioned within the fuel vapor storage canister; and discontinuing the purging the fuel vapors resulting from undesired fuel outflow and/or from the exhaust manifold in response to the canister load reaching the threshold load. - View Dependent Claims (17, 18, 19)
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Specification