Systems and methods for intelligent vehicle evaporative emissions diagnostics

Abstract

The invention provides systems and methods for intelligent vehicle evaporative emissions diagnostics. Methods and systems are provided for conducting tests for undesired evaporative emissions on a vehicle fuel system and evaporative emissions system. In one example, a method may include learning routes commonly traveled by the vehicle, including altitude changes and stop durations, and may furtherinclude diagnosing the fuel system and evaporative emissions system based on the learned altitude changes in one example, and may include diagnosing the fuel system and evaporative emissions system based on a learned stop duration in another example. By conducting tests for undesired evaporative emissions as a function of learned travel routes, completion rates for tests for undesired evaporativeemissions tests may be increased, and the release of undesired evaporative emissions to atmosphere may be reduced.

Description

technical field [0001] The present description generally relates to methods and systems for controlling passive purge events of a fuel vapor storage canister based on a driving route known in advance. Background technique [0002] The vehicle emission control system may be configured to store fuel vapors from fuel tank refueling and daytime engine operation in a fuel vapor storage canister and then purge the stored vapors during subsequent engine operation. In particular, purging stored vapors during engine operation may include commanding open a canister purge valve positioned in a purge line between the engines and commanding a canister vent positioned in a vent line coupling the canister to atmosphere The valve opens. In this way, engine intake manifold vacuum can be applied to the canister whereby atmospheric air is drawn across the canister which desorbs stored fuel vapors from the canister and directs them to the engine for combustion . [0003] However, certain veh...

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Problems solved by technology

Second, this approach relies on specially designed valves (such as vacuum-based valves), which may not be desirable to include in all vehicle fuel systems and which can add to the costs associated with vehicle assembly

Third, such vacuum based valves may only have one set point under which the pressure in the fuel system is reached, thus limiting the ability to exert any level of control over how much the canister can be passively cleaned

As more and more vehicles participate in car-sharing models in which vehicles are rented for short periods of time, such extended vehicle off soak periods may be rare and, therefore, opportunities for passive canister cleaning may be too rare

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