Method of de-pressurizing an evaporative emission control system
AssigneeChrysler Corporation
InventorsWilliam B. Blomquist, Gary D. Dawson, Roland T. Richardson, Glen Tallarek
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Abstract
A method of de-pressurizing an evaporative emission control system includes the steps of pulsing a leak detection pump at a predetermined rate and purging accumulated vapors from a vapor canister. The method also includes the steps of determining whether a last pump period is greater than or equal to a predetermined system de-pressurization mode pump period and continuing the method if the last pump period is less than the system de-pressurization mode pump period.
Claims3
A method of de-pressurizing an evaporative emission control system in a controlled manner, said method comprising the steps of:
- energizing a leak detection pump to close a canister vent control valve of the system and pressurize the system;
- determining if the system has achieved sufficient pressure to conclude no leak has occurred;
- pulsing the leak detection pump at a predetermined rate if no leak has occurred;
- purging accumulated vapors from a vapor canister;
- determining if the engine vacuum level is greater than or equal to a predetermined system de-pressurization minimum vacuum limit;
- ending the method if the engine vacuum level is not greater than or equal to a system de-pressurization mode pump period;
- continuing pulsing the leak detection pump if the engine vacuum level is greater than or equal to the predetermined system depressurization minimum vacuum limit;
- determining whether a last pump period is greater than or equal to the predetermined system de-pressurization mode pump period;
- and
- enabling normal purging if the last pump period is less than the system de-pressurization mode pump period.
A method of de-pressurizing an evaporative emission control system, said method comprising the steps of:
- energizing a leak detection pump to close a canister vent control valve of the system and pressurize the system:
- determining if the system has achieved sufficient pressure to conclude no leak has occurred;
- pulsing the leak detection pump at a predetermined rate if no leak has occurred;
- purging accumulated vapors from a vapor canister;
- determining whether a last pump period is greater than or equal to a predetermined system de-pressurization mode pump period;
- and
- enabling normal purging if the last pump period is less than the system de-pressurization mode pump period.
Dependencies are inferred from the claim text.