ENGINE OFF NATURAL VACUUM LEAKAGE CHECK FOR ONBOARD DIAGNOSTICS
First Claim
1. A diagnostic system for detecting leaks in a vapor handling system of a vehicle, comprising:
- a fuel tank;
a pressure/vacuum sensor that senses pressure and vacuum in said fuel tank;
a canister for recovering vapor from said fuel tank;
a canister vent solenoid for selectively providing atmospheric air to said canister; and
a controller connected to said canister vent solenoid and said pressure/vacuum sensor that executes a leakage detection test that detects leaks in said vapor handling system that have a minimum diameter on the order of 0.020 inch.
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Accused Products
Abstract
A diagnostic method and system detects leaks in a vapor handling system of a vehicle that includes a fuel tank and a pressure/vacuum sensor that senses pressure and vacuum in the fuel tank. A canister recovers vapor from the fuel tank. A canister vent solenoid selectively provides atmospheric air to the canister. A controller connected to the canister vent solenoid and the pressure/vacuum sensor executes a leakage detection test that is capable of detecting leaks in the vapor handling system that have a diameter on the order of 0.020 inch. The leakage detection test includes a volatility test phase, a pressure phase, a vacuum phase, an analysis phase and a results phase. In other features, the leakage detection algorithm generates data sets having greater than 25 standard deviations between leakage and no-leakage data sets.
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Citations
34 Claims
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1. A diagnostic system for detecting leaks in a vapor handling system of a vehicle, comprising:
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a fuel tank;
a pressure/vacuum sensor that senses pressure and vacuum in said fuel tank;
a canister for recovering vapor from said fuel tank;
a canister vent solenoid for selectively providing atmospheric air to said canister; and
a controller connected to said canister vent solenoid and said pressure/vacuum sensor that executes a leakage detection test that detects leaks in said vapor handling system that have a minimum diameter on the order of 0.020 inch. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. The diagnostic system of claim 17 wherein, during said vacuum phase, if said vacuum is zero for a second predetermined period said controller initiates said analysis phase.
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18. A diagnostic method for detecting leaks in a vapor handling system of a vehicle, comprising the steps of:
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sensing pressure and vacuum in a fuel tank of said vehicle;
recovering vapor from said fuel tank using a canister;
selectively providing atmospheric air to said canister using a canister vent; and
executing a leakage detection test using a controller, wherein said leakage detection test detects leaks in said vapor handling system that have a minimum diameter on the order of 0.020 inch. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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Specification