EVAPORATIVE EMISSIONS SYSTEM CHECK VALVE MONITOR FOR A MULTI-PATH PURGE EJECTOR SYSTEM
First Claim
1. A method comprising:
- storing fuel vapors from a fuel system, which supplies fuel to an engine, in a fuel vapor storage canister;
coupling the 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; and
diagnosing whether the second check valve is stuck open based on a temperature change of the canister.
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Accused Products
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.
10 Citations
20 Claims
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1. A method comprising:
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storing fuel vapors from a fuel system, which supplies fuel to an engine, in a fuel vapor storage canister; coupling the 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; and diagnosing whether the second check valve is stuck open based on a temperature change of the canister. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for a vehicle, comprising:
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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 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 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. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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18. A method comprising:
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storing fuel vapors from a fuel system, which supplies fuel to an engine, in a fuel vapor storage canister; coupling the canister to an air intake of the engine through a second path having a second check valve; and during a test condition, drawing a vacuum in the second path through the canister and diagnosing whether the second check valve is stuck open based on a temperature change of the canister. - View Dependent Claims (19, 20)
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Specification