System and methods for a fuel tank pressure control pump
Abstract:
Systems for hybrid electric engines have a fuel vapor canister (FVC) in fluid communication with (i) fuel vapor in a fuel tank with a refueling valve therebetween, (ii) an intake manifold with a canister purge valve therebetween, and (iii) atmospheric pressure (atm) with a canister vent valve (CVV) therebetween, a bypass loop around the refueling valve, and a pressure sensor upstream of both the refueling valve and the CVV. The loop has a control pump and a control valve controlling fluid communication with atm, and in a first mode, control valve and CVV open, pumps fuel vapor to the FVC for pressure control, then closes the control valve; in a second mode, control valve closed and CVV open, pumps atm to the FVC; and in a third mode, control valve and CVV open, pumps fuel vapor to the FVC to a pre-selected threshold to close the CVV.
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