Systems and methods for detection and mitigation of liquid fuel carryover in an evaporative emissions system
First Claim
1. A method for a fuel system, comprising:
- during a first condition, activating a vacuum pump to pressurize the fuel system responsive to a first fuel tank pressure decay rate being less than a threshold; and
responsive to a second fuel tank pressure decay rate being greater than the threshold, maintaining the vacuum pump on until a fuel tank pressure decreases to atmospheric pressure.
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Accused Products
Abstract
Methods and systems are provided for detecting and mitigating the presence of liquid fuel carryover in an evap system of a vehicle in response to a refueling event. In one example, during a first condition, a vacuum pump is activated to pressurize the fuel system responsive to a first fuel tank pressure decay rate being less than a threshold, and responsive to a second fuel tank pressure decay rate being greater than a threshold, the vacuum pump is maintained on until a fuel tank pressure decreases to atmospheric pressure. In this way, liquid fuel carryover can be quickly and accurately diagnosed, such that mitigating actions may be taken to ensure liquid fuel is returned to the tank prior to contacting the adsorbent material within the vapor canister.
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Citations
19 Claims
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1. A method for a fuel system, comprising:
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during a first condition, activating a vacuum pump to pressurize the fuel system responsive to a first fuel tank pressure decay rate being less than a threshold; and responsive to a second fuel tank pressure decay rate being greater than the threshold, maintaining the vacuum pump on until a fuel tank pressure decreases to atmospheric pressure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for a fuel system, comprising:
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following a refueling event, monitoring a fuel tank pressure bleed-down rate; indicating a presence of liquid fuel in an evap recovery line responsive to a first fuel tank pressure bleed-down rate less than a threshold; actively returning the liquid fuel in the evap recovery line to a fuel tank; and responsive to the first fuel tank pressure bleed-down rate being greater than the threshold, sealing the fuel tank responsive to a fuel tank pressure decreasing to atmospheric pressure, and updating a canister purge schedule. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A fuel system, comprising:
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a fuel tank coupled to a fuel vapor canister via one or more evap recovery lines; a fuel tank isolation valve coupled between the fuel tank and the fuel vapor canister; a fuel tank pressure sensor; a fuel tank fill level sensor; an evaporative leak check module comprising a reversible vacuum pump coupled between the fuel vapor canister and atmosphere; and a controller storing instructions in non-transitory memory that, when executed, cause the controller to; receive a request for a refueling event; open the fuel tank isolation valve; monitor a fuel tank pressure via the fuel tank pressure sensor and a fuel tank fill level via the fuel tank fill level sensor for a duration of the refueling event; indicate liquid fuel carryover into the one or more evap recovery lines responsive to a first fuel tank pressure decay rate following the refueling event being less than a threshold; and responsive to an indication of liquid fuel carryover into the one or more evap recovery lines, activate the reversible vacuum pump to direct atmospheric air into the fuel system. - View Dependent Claims (18, 19)
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Specification