Fuel oxidation reduction for hybrid vehicles
First Claim
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1. A method, comprising:
- responsive to fuel tank pressure below a threshold, routing fuel vapors from a fuel system canister to the fuel tank to maintain the fuel tank pressure at a desired pressure;
sensing hydrocarbon concentration of the fuel vapors exiting the canister and entering the fuel tank; and
stopping the routing responsive to an indication that atmospheric air comprising oxygen is being introduced into the fuel tank.
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Abstract
Systems and methods to control fuel tank pressure to reduce fuel oxidation in plug-in hybrid electric vehicles are disclosed. A method comprises routing vapors from a fuel system canister to the fuel tank to maintain the fuel tank pressure at a desired pressure. In this way, the engine may be maintained off for greater durations while still retaining fuel quality of fuel stored on-board the vehicle.
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Citations
11 Claims
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1. A method, comprising:
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responsive to fuel tank pressure below a threshold, routing fuel vapors from a fuel system canister to the fuel tank to maintain the fuel tank pressure at a desired pressure; sensing hydrocarbon concentration of the fuel vapors exiting the canister and entering the fuel tank; and stopping the routing responsive to an indication that atmospheric air comprising oxygen is being introduced into the fuel tank. - View Dependent Claims (2, 3, 4, 5)
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6. A system for reducing fuel oxidation, comprising:
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a fuel tank; a pressure sensor to sense vapor pressure within the fuel tank; a vapor canister coupled to atmosphere via a diverter line and coupled to the fuel tank via a vapor line; a fuel tank isolation valve positioned in the vapor line; a diverter valve positioned in the diverter line; a hydrocarbon sensor positioned between the fuel tank and the fuel vapor canister; and a controller storing instructions in non-transitory memory, that when executed, cause the controller to; responsive to an indication that fuel tank pressure is below a threshold, actuating open the diverter valve to pull air into the canister, pushing hydrocarbon vapors into the fuel tank to mitigate negative fuel tank pressure; monitor a hydrocarbon concentration in the vapor line via the hydrocarbon sensor; and in a first condition, close the diverter valve responsive to fuel tank pressure above the threshold; and in a second condition, close the diverter valve responsive to hydrocarbon concentration below a threshold; wherein closing the diverter valve responsive to hydrocarbon concentration below the threshold prevents atmospheric air comprising oxygen into the fuel tank. - View Dependent Claims (7, 8, 9, 10, 11)
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Specification