A fuel vapor recovery system is disclosed that includes a fuel tank and a filler neck that port fuel vapor to a vapor storage canister. Data is received from onboard or external sources that indicate a quantity of dust particles in the environment of the vehicle. A controller responsive to the data indicating the quantity of dust controls a valve to provide purge air received through a dust box to the vapor storage canister when the quantity of dust particles is below a predetermined threshold. The valve is switched to provide purge air from an engine intake system to the vapor storage canister when the quantity of dust particles is above the predetermined threshold.

A method for testing the function of a fuel tank system of an internal combustion engine, the fuel tank system, whereby a gas transport device is operated and a shutoff valve is actuated by means of PWM, whereby the shutoff valve is opened and closed multiple times according to a PWM signal for implementing a defined opening state, a pressure oscillation of the purge gas, which results due to the corresponding opening and closing movements of the shutoff valve, being ascertained and evaluated with the aid of the pressure sensor according to a frequency diagnosis, and a distinction being made between an operability and a malfunction, based on the result of the evaluation.

A fuel vapor emissions control device includes: —an absorbent filter; —a purge circuit including: a pump equipped with an intake and with a delivery outlet; an upstream duct; and a downstream duct. The pump includes an intake chamber into which the intake opens. The upstream duct is connected by one of its ends to the absorbent filter and via the other of its ends opens into the intake chamber. The downstream duct includes a double tubular wall defining two separate conduits.

In a fuel tank system, a control unit diagnoses a failure of a fuel storage unit and a processing unit. The fuel storage unit includes a vapor passage through which a fuel tank and a sealing valve are communicated with each other, a first pressure detection unit, and a second pressure detection unit disposed at a position different from the first pressure detection unit. The control unit specifies a presence or an absence of a clogging of the vapor passage based on a first pressure value detected by the first pressure detection unit and a second pressure value detected by the second pressure detection unit when the pressure in the fuel tank is changed by the pressure generation unit in a condition that the sealing valve is controlled to be opened.

The present invention relates to leakage detection unit (100) comprise of an upper housing (5), a lower housing (6) accommodating an electromechanical valve (1), a pump assembly (2), a pressure sensor (3) and a bush (4), wherein the pump assembly (2) includes a pump that permits flow of air that, due to which pressure in passage of the pump becomes constant after a time interval and that pressure is considered as reference pressure. The pressure is measured by help of the pressure sensor (3) and in case the measured pressure is not equal or above to the reference pressure than there is leakage in the isolation valve (100), whereas in case the measured pressure is equal or above the reference pressure that there is no leakage or some permissible amount of leakage in the fuel tank within the time interval.

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.

A failure diagnostic apparatus for a fuel vapor treatment device includes a case, a fuel inflow means, and a fuel discharge means. The case is disposed inside the fuel tank. A canister is accommodated in the case. The case shields the canister from the fuel in the fuel tank and provides a gap between an inner surface of the case and an outer surface of the canister. The fuel inflow means is activated when the fuel tank is refueled, and allows the fuel in the fuel tank to flow into the case. The fuel discharge means is activated during failure diagnosis by the failure diagnostic means, and drains the fuel in the case into the fuel tank.

A method for testing the function of a fuel tank system of an internal combustion engine, the fuel tank system, whereby a gas transport device is operated and a shutoff valve is actuated by means of PWM, whereby the shutoff valve is opened and closed multiple times according to a PWM signal for implementing a defined opening state, a pressure oscillation of the purge gas, which results due to the corresponding opening and closing movements of the shutoff valve, being ascertained and evaluated with the aid of the pressure sensor according to a frequency diagnosis, and a distinction being made between an operability and a malfunction, based on the result of the evaluation.

A pressure sensor for an evaporated fuel leak detector is used for checking airtightness in a fuel tank and a canister. The pressure sensor includes a sensor unit, a case, and a sealing resin. The sensor unit has a pressure receiving portion, a plurality of conduction terminals, and a mold resin portion. The case has a fluid flow path and a housing recess. A buffer recess having an outer shape larger than the outer shape of a pressure receiving surface is formed at a pressure receiving side L1 of the bottom of the housing recess. Further, a protruding cylinder portion protruding into the buffer recess toward a back side L2 is formed at an outer edge of an opening end portion of the fluid flow path on the back side L2.

In an evaporative fuel treatment device, a differential pressure specifying unit specifies a differential pressure between a pressure in a diagnosis target system and the atmosphere, and a pressure target setting unit sets a pressure target value so that the differential pressure attains a predetermined differential pressure value. A pump pressurizes or depressurizes the pressure in the diagnosis target system to the pressure target value, and a leakage diagnosis unit performs a leakage diagnosis based on a pressure change relation value related to the pressure change in the diagnosis target system and the leakage diagnosis threshold value. The fuel partial pressure estimation unit estimates a first partial pressure of fuel vapor in the fuel tank from a tank inside concentration and a tank absolute pressure of a specific component. A corresponding partial pressure specifying unit specifies a second partial pressure of the fuel vapor in the fuel tank based on a relation between the tank absolute pressure and the first partial pressure when the second partial pressure of the fuel vapor in the fuel tank when the pressure is increased or reduced to the target pressure value. A comparison unit compares the first partial pressure and the second partial pressure. A correction unit corrects, based on a comparison result of the comparison unit, a leakage diagnosis threshold value or the pressure change relation value used for the leakage diagnosis.