Systems and methods for reducing vehicle emissions
Methods and systems are provided for taking mitigating action where a canister purge valve configured to control an amount of fuel vapors inducted into the engine during purging operations of a fuel vapor storage canister, is indicated as being degraded. In one example, a method comprises controlling an amount of pressure directed to a fuel tank and the fuel vapor storage canister via a pump positioned downstream of the fuel tank and canister to actively route fuel vapors to the canister during a refueling event. In this way, fuel vapors may be prevented from being routed to engine intake under conditions of a degraded canister purge valve, which may reduce opportunity for vehicle stall, improve driveability, and which may reduce release of undesired evaporative emissions to atmosphere.
1. A method, comprising:
controlling an amount of pressure directed to a fuel tank that supplies fuel to an engine of a vehicle, and to a fuel vapor storage canister receiving fuel vapors from the fuel tank, via a pump positioned downstream of the fuel tank and the fuel vapor storage canister, to actively route fuel vapors to the fuel vapor storage canister during a refueling event where fuel is added to the fuel tank.
2. The method of claim 1 , wherein the pump includes the engine, and wherein directing pressure to the fuel tank and to the fuel vapor storage canister via the pump includes rotating the engine unfueled in reverse.
3. The method of claim 1 , wherein the pump includes a purge pump positioned in a purge line coupling the engine to the fuel vapor storage canister, and wherein directing pressure to the fuel tank and to the fuel vapor storage canister includes rotating the purge pump in a reverse-mode of operation.
4. The method of claim 1 , wherein the refueling event includes an indication that a canister purge valve configured to selectively couple the engine to the fuel vapor storage canister and the fuel tank is degraded.
5. The method of claim 1 , wherein controlling the amount of pressure directed to the fuel tank and to the fuel vapor storage canister includes controlling the amount of pressure to avoid inducing an automatic shutoff of a refueling dispenser due to the pressure directed to the fuel tank and to the fuel vapor storage canister.
6. The method of claim 1 , wherein controlling the amount of pressure directed to the fuel tank and to the fuel vapor storage canister prevents fuel vapors generated during the refueling event from being routed to the engine.
7. The method of claim 1 , wherein controlling the amount of pressure directed to the fuel tank and to the fuel vapor storage canister is based on a fuel tank pressure and a pressure in an intake manifold of the engine while the pump is activated to direct pressure to the fuel tank and to the fuel vapor storage canister.
8. The method of claim 1 , further comprising reversing a direction that the pump is operating in response to an indication of breakthrough of fuel vapors from the fuel vapor storage canister during the refueling event, to stop routing fuel vapors to the fuel vapor storage canister and to instead route fuel vapors to an exhaust catalyst positioned in an exhaust system of the engine.
9. The method of claim 8 , wherein routing fuel vapors to the exhaust catalyst further comprises raising a temperature of the exhaust catalyst to a threshold temperature if the temperature of the exhaust catalyst is not already at or above the threshold temperature when the breakthrough of fuel vapors from the fuel vapor storage canister occurs.
10. The method of claim 1 , wherein the pump is selected as a function of an energy storage level of an onboard energy storage device.
11. A method, comprising:
actively routing fuel vapors to a fuel vapor storage canister configured to receive fuel vapors from a fuel tank in a vehicle, the fuel tank supplying fuel to an engine, during a refueling event where a canister purge valve configured to selectively couple the fuel vapor storage canister to the engine is degraded, and where actively routing the fuel vapors involves activating a pump positioned downstream of the fuel tank and the fuel vapor storage canister.
12. The method of claim 11 , wherein the canister purge valve being degraded includes an indication that the canister purge valve is not capable of fully closing.
13. The method of claim 11 , wherein actively routing fuel vapors to the fuel vapor storage canister prevents fuel vapors from being introduced to the engine during the refueling event.
14. The method of claim 11 , wherein actively routing fuel vapors to the fuel vapor storage canister further comprises controlling the pump to regulate a pressure amount directed to the fuel tank and the fuel vapor storage canister.
15. The method of claim 14 , wherein controlling the pump to regulate the pressure amount directed to the fuel tank and the fuel vapor storage canister is a function of a fuel tank pressure and a pressure in an intake manifold of the engine.
16. The method of claim 11 , wherein the pump is selected via a controller and where the pump is one of a purge pump positioned between the fuel vapor storage canister and the canister purge valve, or the engine;
wherein under conditions where the purge pump is selected, activating the pump includes activating the purge pump in a reverse-mode of operation; and
wherein under conditions where the engine is selected, activating the pump includes rotating the engine unfueled in reverse.
17. The method of claim 11 , further comprising monitoring a vent line coupling the fuel vapor storage canister to atmosphere for breakthrough of fuel vapors from the fuel vapor storage canister during the actively routing fuel vapors to the fuel vapor storage canister, and in response to an indication of breakthrough of fuel vapors, stopping actively routing the fuel vapors to the fuel vapor storage canister, and re-routing the fuel vapors to an exhaust catalyst positioned in an exhaust system of the engine.