Vapor purge system integrity diagnosis for a hybrid vehicle
First Claim
1. A method to test a vapor purge system (VPS) for an internal combustion engine in a hybrid vehicle, the method comprising:
- measuring a pressure in the VPS;
closing a first valve coupling a carbon canister of the VPS and atmosphere;
decreasing pressure in the VPS if the pressure is greater than a threshold, the pressure decreased by;
opening a second valve coupling the fuel tank and the engine while the engine is running; and
closing the second valve when the pressure is below the threshold to provide a variable starting pressure in the VPS related to a manifold pressure for the engine; and
monitoring pressure in the VPS for a predetermined time period to test for system integrity when the engine is at rest and the vehicle is operating.
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Abstract
A method for testing a vapor purge system (VPS), and the vehicle having the VPS, including a controller for measuring a VPS pressure, closing a first valve coupling a VPS carbon canister and the environment, decreasing VPS pressure if it is greater than a threshold, and monitoring VPS pressure for a time period when the engine is at rest and the vehicle is operating. The pressure is decreased by opening a second valve coupling the fuel tank and the engine while the engine is running, and closing the second valve when the pressure is below the threshold. Another method for testing a VPS includes closing a first valve, closing a second valve, measuring the VPS pressure to provide a reference pressure with an associated profile, and monitoring VPS pressure compared to the profile for a time period.
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Citations
20 Claims
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1. A method to test a vapor purge system (VPS) for an internal combustion engine in a hybrid vehicle, the method comprising:
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measuring a pressure in the VPS; closing a first valve coupling a carbon canister of the VPS and atmosphere; decreasing pressure in the VPS if the pressure is greater than a threshold, the pressure decreased by; opening a second valve coupling the fuel tank and the engine while the engine is running; and closing the second valve when the pressure is below the threshold to provide a variable starting pressure in the VPS related to a manifold pressure for the engine; and monitoring pressure in the VPS for a predetermined time period to test for system integrity when the engine is at rest and the vehicle is operating. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 20)
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10. A hybrid electric vehicle (HEV) comprising:
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an engine; an electric machine; a vapor purge system (VPS) with a pressure transducer and a carbon canister coupled to atmosphere via a first valve and coupled to the engine via a second valve; and a controller configured to (i) close the first valve, (ii) close the second valve when the pressure in the VPS is less than a predetermined threshold value to provide a variable starting pressure, and (iii) monitor pressure in the VPS using the pressure transducer while the vehicle is operating and the engine is at rest. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A method to test a vapor purge system (VPS) for an internal combustion engine comprising:
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closing a first valve coupled between a carbon canister and environment; closing a second valve coupled between the canister and the engine to provide a variable starting pressure in the VPS; measuring the starting pressure to provide a related reference value having an associated threshold profile that varies with time; and monitoring pressure in the VPS compared to the associated threshold profile over a predetermined time period. - View Dependent Claims (17, 18, 19)
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Specification