Fuel system leak check based on fuel reid vapor pressure
First Claim
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1. A method for an evaporative emissions leak test, comprising:
- adjusting a pressure threshold based on a fuel volatility of a fuel contained in a fuel tank; and
performing the evaporative emissions leak test based on the adjusted pressure threshold, where the fuel volatility is determined by;
venting fuel vapor from the fuel tank to a fuel vapor canister; and
determining a hydrocarbon percentage of the vented fuel vapor with a hydrocarbon sensor coupled between the fuel tank and the fuel vapor canister.
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Abstract
A method for an evaporative emissions leak test, comprising: adjusting a pressure threshold based on a fuel volatility of a fuel contained in a fuel tank; and performing the evaporative emissions leak test based on the adjusted pressure threshold. By determining fuel volatility and adjusting a pressure threshold based on the fuel volatility, a more robust and accurate evaporative emissions leak test may be employed without adding additional components to a fuel system.
19 Citations
20 Claims
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1. A method for an evaporative emissions leak test, comprising:
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adjusting a pressure threshold based on a fuel volatility of a fuel contained in a fuel tank; and performing the evaporative emissions leak test based on the adjusted pressure threshold, where the fuel volatility is determined by; venting fuel vapor from the fuel tank to a fuel vapor canister; and determining a hydrocarbon percentage of the vented fuel vapor with a hydrocarbon sensor coupled between the fuel tank and the fuel vapor canister. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for an evaporative emissions system leak test, comprising:
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determining a reference vacuum threshold; venting fuel vapor from a fuel tank; determining a fuel Reid Vapor Pressure of the fuel vapor; adjusting the reference vacuum threshold based on the fuel Reid Vapor Pressure; drawing a vacuum on a fuel tank with an evaporative leak check module; and indicating degradation of the evaporative emissions system based on the adjusted reference vacuum threshold. - View Dependent Claims (12, 13, 14, 15)
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16. A method for an evaporative emissions system leak test, comprising:
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responsive to an engine off condition, closing a canister vent valve; determining a resulting pressure of a fuel tank; determining a Reid Vapor Pressure of a fuel in the fuel tank; determining a threshold pressure based on the fuel Reid Vapor Pressure; and comparing the resulting pressure of the fuel tank to the threshold pressure. - View Dependent Claims (17, 18, 19)
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20. A method for an evaporative emissions leak test, comprising:
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where the evaporative emissions leak test is an evaporative leak check module based test, isolating an evaporative leak check module from a fuel tank; activating a vacuum pump comprising the evaporative leak check module; drawing a vacuum across a reference orifice; setting a pressure threshold based on the vacuum drawn across the reference orifice; adjusting the pressure threshold based on a fuel volatility of a fuel contained in the fuel tank; and performing the evaporative emissions leak test based on the adjusted pressure threshold.
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Specification