Leak detection for a vapor handling system
First Claim
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1. A method of detecting a leak in a fuel vapor emission control system of an internal combustion engine driven vehicle, said fuel vapor system comprising a fuel tank including a fuel vapor temperature sensor and a tank pressure sensor;
- a vapor vent line leading from said tank to a fuel vapor adsorption canister, said canister comprising a vapor vent/air inlet line including a vent valve and a vapor purge line including a purge valve, said vent and purge valves being operated under the control of an emission control system computer module, said method to be executed by operation of said computer and comprising the steps of,closing said purge valve, if necessary, and said vent valve following engine shut-off, sensing said fuel vapor temperature and tank pressure during a period of time when said engine is shut off and said fuel vapor temperature is decreasing, recording said pressure and temperature during said period, opening said vent valve, and providing an indication of no detectable system leak if said pressure decreases below atmospheric pressure, or recording an indication of system leak if said pressure does not fall below atmospheric pressure, during said time period, wherein prior to closing said canister vent valve, determining that the fuel content of the fuel tank is in the range of about 15% to 85% of the capacity of the tank, and if the fuel content is not in said range, shutting down said computer to abort the leak detection test.
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Abstract
The engine or powertrain control module of a vehicle remains electrically powered after the engine is stopped and is used to assess whether there is a leak in the evaporative emissions control system. Fuel tank temperature and pressure data, as well as fuel level data, is analyzed over a brief period of time by module and, if ambient conditions are suitable, the vent on the fuel adsorption canister is closed by signal from the module. The system is thus sealed and the module then analyzes the system pressure changes over a second brief period as the fuel cools by heat loss to detect the vacuum that will occur if the system has no leak.
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Citations
2 Claims
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1. A method of detecting a leak in a fuel vapor emission control system of an internal combustion engine driven vehicle, said fuel vapor system comprising a fuel tank including a fuel vapor temperature sensor and a tank pressure sensor;
- a vapor vent line leading from said tank to a fuel vapor adsorption canister, said canister comprising a vapor vent/air inlet line including a vent valve and a vapor purge line including a purge valve, said vent and purge valves being operated under the control of an emission control system computer module, said method to be executed by operation of said computer and comprising the steps of,
closing said purge valve, if necessary, and said vent valve following engine shut-off, sensing said fuel vapor temperature and tank pressure during a period of time when said engine is shut off and said fuel vapor temperature is decreasing, recording said pressure and temperature during said period, opening said vent valve, and providing an indication of no detectable system leak if said pressure decreases below atmospheric pressure, or recording an indication of system leak if said pressure does not fall below atmospheric pressure, during said time period, wherein prior to closing said canister vent valve, determining that the fuel content of the fuel tank is in the range of about 15% to 85% of the capacity of the tank, and if the fuel content is not in said range, shutting down said computer to abort the leak detection test.
- a vapor vent line leading from said tank to a fuel vapor adsorption canister, said canister comprising a vapor vent/air inlet line including a vent valve and a vapor purge line including a purge valve, said vent and purge valves being operated under the control of an emission control system computer module, said method to be executed by operation of said computer and comprising the steps of,
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2. A method of detecting a leak in a fuel vapor emission control system of an internal combustion engine driven vehicle, said fuel vapor system comprising a fuel tank including a fuel vapor temperature sensor and a tank pressure sensor;
- a vapor vent line leading from said tank to a fuel vapor adsorption canister, said canister comprising a vapor vent/air inlet line including a vent valve and a vapor purge line including a purge valve, said vent and purge valves being operated under the control of an emission control system computer module, said method to be executed by operation of said computer and comprising the steps of,
closing said purge valve, if necessary, and said vent valve following engine shut-off, sensing said fuel vapor temperature and tank pressure during a period of time when said engine is shut off and said fuel vapor temperature is decreasing, recording said pressure and temperature during said period, opening said vent valve, and providing an indication of no detectable system leak if said pressure decreases below atmospheric pressure, or recording an indication of system leak if said pressure does not fall below atmospheric pressure, during said time period, wherein prior to closing said canister vent valve, determining that the ambient temperature is above about 40°
F., and if the ambient temperature is not above said temperature, shutting down said computer to abort the leak detection test.
- a vapor vent line leading from said tank to a fuel vapor adsorption canister, said canister comprising a vapor vent/air inlet line including a vent valve and a vapor purge line including a purge valve, said vent and purge valves being operated under the control of an emission control system computer module, said method to be executed by operation of said computer and comprising the steps of,
Specification
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Current AssigneeGM Global Technology Operations LLC (General Motors Company)
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Original AssigneeGeneral Motors Corporation (General Motors Company)
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InventorsMc Carthy, Timothy E., Rich, Gregory Earl, Labus, Gregory Edward, Reddy, Sam Raghuma
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Primary Examiner(s)Yuen, Henry C.
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Assistant Examiner(s)Gimie, Mahmoud
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Application NumberUS09/492,400Time in Patent Office670 DaysField of Search123/520, 123/516, 123/519, 123/198.D, 731/181, 73/40US Class Current123/520CPC Class CodesF02M 25/0809 Judging failure of purge co...
