Evaporative emissions system check valve monitor for a multi-path purge ejector system
AssigneeFord Global Technologies, LLC
InventorAed M. Dudar
Life of this patent
Estimating the term…
Abstract
Methods and systems are provided for diagnosing functionality of a check valve in a vehicle evaporative emissions system, where the check valve functions to prevent unmetered air from entering engine intake under conditions of engine intake manifold vacuum. In one example, a method may include diagnosing whether the check valve is stuck open based on a temperature change at the fuel vapor canister as monitored by a canister temperature sensor, and responsive to an indication that the check valve is stuck open, taking mitigating actions to reduce undesired emissions. In this way, functionality of such a check valve may be determined periodically, without additional sensors, thus reducing costs while improving emissions.
Claims19
A method comprising:
- storing fuel vapors from a fuel system, which supplies fuel to an engine, in a fuel vapor storage canister;
- coupling the fuel vapor storage canister to an air intake of the engine through a second path having a second check valve which prevents unmetered air from being drawn into an intake manifold of the engine when a canister purge valve is open;
- diagnosing whether the second check valve is stuck open based on a temperature change of the fuel vapor storage canister;
- preventing positive pressure with respect to atmospheric pressure from being communicated to the fuel vapor storage canister under conditions of positive pressure in the intake manifold via a first check valve in a first path;
- and
- wherein diagnosing whether the second check valve is stuck open includes an indication that the first check valve is not stuck open.
A system for a vehicle, comprising:
- an engine operable under boosted and natural aspiration conditions;
- a fuel system including a fuel tank which supplies fuel to the engine, selectively coupled to an evaporative emissions system via a fuel tank isolation valve;
- a fuel vapor storage canister positioned in the evaporative emissions system;
- an onboard pump, positioned in a vent line between the fuel vapor storage canister and atmosphere, the pump including a changeover valve configurable in a first and a second position;
- one or more temperature sensor(s) positioned in the fuel vapor storage canister;
- a pressure sensor positioned in a conduit between the fuel system and the evaporative emissions system;
- a canister purge valve positioned in a purge line downstream of the fuel vapor storage canister;
- a first check valve, positioned between the canister purge valve and an intake manifold of the engine;
- a second check valve, positioned between the canister purge valve and an ejector system;
- and
- a controller storing instructions in non-transitory memory that, when executed, cause the controller to:
- in a first condition, indicate whether the first check valve is stuck open based on a monitored pressure change in the fuel system and the evaporative emissions system during boosted engine operation;
- and
- in a second condition, indicate whether the second check valve is stuck open based on a monitored fuel vapor canister temperature change during an engine-off condition, where the second condition includes an indication that the first check valve is not stuck open.
A method comprising:
- storing fuel vapors from a fuel system, which supplies fuel to an engine, in a fuel vapor storage canister;
- coupling the fuel vapor storage canister to an air intake of the engine through a second path having a second check valve;
- during a test condition, drawing a vacuum in the second path through the fuel vapor storage canister and diagnosing whether the second check valve is stuck open based on a temperature change of the fuel vapor storage canister;
- and
- preventing positive pressure with respect to atmospheric pressure from being communicated to the fuel vapor storage canister during conditions of positive pressure in an intake manifold via a first check valve in a first path.
Dependencies are inferred from the claim text.