A fuel tank system includes a fuel storage unit, a processing unit, and a control unit. The control unit performs a first failure diagnosis of diagnosing a failure of the fuel storage unit in a state where the sealing valve is closed. When the control unit diagnoses that the fuel storage unit is normal, the control unit performs a second failure diagnosis of diagnosing a failure of a purge valve and a bypass valve by causing a pressure generation unit to generate pressure in a state where the sealing valve is closed. When there is a possibility that the purge valve and the bypass valve are in closed-sticking, the control unit performs a third failure diagnosis of specifying a failure in any one of closed-sticking of the purge valve and closed-sticking of the bypass valve by opening the sealing valve.

A fuel vapor processing apparatus may include a canister. A negative pressure applying device for applying a negative pressure to the canister may be disposed in a purge passage communicating between the canister and an intake pipe of an engine. A pressure adjusting device may be disposed in a portion of the purge passage communicating between the fuel tank and the negative pressure applying device.

A fuel vapor processing apparatus includes a canister housing an adsorbent material that adsorbs fuel vapor from a tank, and a valve in a passage connecting the canister and tank. When a stroke amount is within a range, the valve is closed to close the tank and a valve opening start position is learned. In the learning, the stroke amount is varied in the opening direction by repeatedly changing in the opening direction by a first stroke and maintaining for a first time period, and subsequently changing in a closing direction by a second stroke and maintaining for a second time period. The valve opening start position is determined based on the stroke amount in the second time period when the tank pressure is reduced by the predetermined value or more or in a preceding process.

A purge control solenoid valve includes a gas access body including an evaporation gas inlet, an evaporation gas outlet, and a path that connects the evaporation gas inlet and the evaporation gas outlet; a valve operation body including an armature coupled to the gas access body and performing a reciprocating motion in a direction in which the armature is brought into close contact with or separated from the path by a core that generates a magnetic force; and an armature top member being in close contact with or separated from the path due to the reciprocating motion of the armature to open or close the path. The armature top member has a non-adhesion coating formed on a top surface of a body thereof, and the non-adhesion coating includes a binder, graphite, polytetrafluoroethylene, and a crosslinking agent.

A tank venting system in accordance with the present disclosure includes a vent apparatus for regulating flow of fuel vapor between a fuel tank and a fuel vapor recovery system in a vehicle. The flow of fuel vapor is controlled to maintain the pressure of fuel vapor in the fuel tank at a certain pressure level or within a certain pressure range during different modes of use.

The disclosure relates to a method for ascertaining the flow through a timer valve. The method includes detecting the pressure upstream of the timer valve during an evacuation of a container arranged upstream of the timer valve, ascertaining the flow through the timer valve based on the detected pressure upstream of the timer valve and based on the temperature and the volume of the gas in the container. The method also includes comparing the flow ascertained during the evacuation and a modeled flow and/or comparing a variable dependent on the ascertained flow and a variable dependent on the modeled flow. Additionally, the method includes adapting the model in the event of a discrepancy between the flow ascertained during the evacuation and the modeled flow and/or in the event of a discrepancy between the variable dependent on the ascertained flow and the variable dependent on the modeled flow.

Disclosed is a method for diagnosing sealing in a fuel vapor recirculation system for an engine of a motor vehicle. An electronic module is integrated into the engine control unit that is woken up and placed on standby periodically while the engine is off, at the start and end of time intervals in order to perform a respective leak diagnosis, the fuel vapor temperature Tsys being estimated as a function of a time t ending at the start of each interval and starting when the engine is switched off according to the following equation, in which Tamb is the ambient temperature measured, Tsys0 is the fuel vapor temperature when the vehicle is switched off, and tsys is a system response time:
Tsys(t)=Tamb+(Tsys0−Tamb)e.sup.−t/tsys.

A valve is provided having a circuit that includes an electrical conductor with a temperature-dependent electrical resistance. The electrical conductor is connected in series to an electrical series resistor, which includes a parallel circuit of a non-reactive wire and an NTC resistor. The electrical conductor includes a coil wire wound into a magnetic coil that is operable to move an armature to open or close the valve. The effect of the operation of the valve itself on the magnetic force of the coil is minimized by arranging the NTC resistor to be thermally coupled with the coil wire.

A valve, controlling pressure differential by regulating fluid flow between a tank and a canister, includes: a valve opening; a first moving element carrying a first sealing device making a leaktight seal and movable relative to the valve opening between a closed and an opened position allowing a first flow between the tank and the canister, through a first passageway with a first size; a second moving element carrying a second sealing device making a leaktight seal and movable relative to the valve opening between a closed and an opened position allowing a second flow between the tank and the canister, through a second passageway with a second size. The second moving element includes a central hole having a frustoconical surface partly defining the first passageway. The first sealing device has a complementary frustoconical surface cooperating with the frustoconical surface of the central hole of the second moving element.

A failure diagnostic device is configured to determine saturated vapor pressures of a fuel within a fuel tank. In a fuel vapor processing apparatus, some or all of the passages and spaces into which the fuel vapor flows into the fuel vapor processing apparatus are closed to the atmosphere. In this condition, the failure diagnostic device determines a plurality of saturated vapor pressure characteristics over time. The failure diagnostic device is configured to diagnose whether or not a leakage or a blockage failure in the fuel vapor processing apparatus is present. The failure diagnostic device determines a Reid vapor pressure (RVP) based on each of the plurality of determined saturated fuel vapor pressure characteristic and diagnoses whether or not a failure is present in accordance with a change in these RVPs over time.