Abstract: In a system and a method for purging a vapor storage canister having adsorbed fuel vapor (or hydrocarbon vapor) by drawing air through the storage canister the storage canister being coupled with an engine having a system for controlling the amount of fuel provided to the engine, the amount of fuel vapor in the purge is estimated using a model that predicts fuel vapor concentration in the purge vapor. The engine controller uses the estimated amount of fuel vapor and air brought into the engine from the evaporative vapor storage canister for better control of engine air and fuel during purging.

Abstract: A lag time is set in a period from the time when a leak down is finished to the time when measurement of the amount of fuel vapor is started for the purpose of returning a deformed fuel tank to its original shape. A fuel vapor amount estimating means is provided that estimates the amount of fuel vapor produced in the fuel tank during the time of the leak down. This means is so set as to make the lag time shorter as the amount of fuel vapor increases. With this, undesired precision in measuring the amount of fuel vapor produced under a condition wherein the amount of fuel vapor is large can be avoided.

Abstract: A family of canisters that includes at least two canisters that are adapted to filter a flow of fluid from a fuel tank. Each canister includes a first portion that defines a first perimeter and a first area each common to all canisters of the family. A second portion defines a second perimeter and a second area each common to all canisters of the family. A cover portion defines a third perimeter and a third area each common to all canisters of the family. A body portion cooperates with the first portion, the second portion, and the cover portion to define an interior space having a volume, a characteristic dimension, and a characteristic length. The volume of each canister of the family is different and the ratio of the characteristic length to characteristic dimension of each of the canisters is between about 1.5 and 5.

Abstract: A fuel vent valve is not shut improperly by the flow of fuel vapor. The fuel vent valve also prevents fuel from spilling out from filler neck during filling of a fuel tank. The fuel vent valve includes a casing having a vent space, a float and a vent device which can be moved up and down. The vent device includes an upper valve member, which shuts and opens a communication passage. The upper valve member is located above the float. A breathing hole and an outer wall of the valve device form a restricted passage. When the fuel level reaches a first predetermined level and the valve device rises, the restricted passage increases the flow resistance to restrict the flow of fuel vapor from the communication passage to the outside of the fuel tank. When fuel level reaches a second predetermined level and the valve device rises further, the upper valve member closes the communication passage.

Abstract: An evaporative emissions control system for small internal combustion engines, including a charcoal canister which is in fluid communication with the air space above the liquid fuel within the carburetor of the engine and the air space above the liquid fuel within the fuel tank of the engine. The charcoal canister contains charcoal media, and when the engine is not running, fuel vapors from the carburetor and the fuel tank migrate to, and are trapped within, the charcoal media of the charcoal canister. The charcoal canister may comprise a separate component, or may be integrally formed with an engine component such as the air cleaner, the carburetor, or the body of the fuel tank, for example. During running of the engine, vacuum within the carburetor induces a flow of atmospheric air through the charcoal canister to purge the collected fuel vapors from the charcoal media, and the fuel vapors pass into the engine for consumption.

Abstract: Pressure detection means detects the pressure of an evaporation purge system that includes a fuel tank and a communicating tube, which connects a canister for adsorbing and retaining fuel vapor to an intake pipe. Shutout means shuts out the evaporation purge system from atmospheric air. A pump is driven for pressurization or depressurization purposes while the shutout means shuts out the evaporation purge system from atmospheric air. The pump is stopped when the pressure detected by the pressure detection means reaches a predetermined level. A leak judgment is formulated in accordance with pump drive time and a pressure change after pump stoppage.

Abstract: A combination fuel vapor storage canister and vapor vent/tipping valve in a common housing with ports for connection to a fuel tank, a purge line and an atmospheric vent. The vapor vent/tipping valve includes a pressure relief valve which prevents vapor venting until a predetermined vapor pressure is reached; and, the pressure relief valve may also include a vacuum relief valve.

Abstract: A valve for a fuel tank includes an upper space or chamber communicating with a ventilation channel; a lower chamber disposed inside a fuel tank; a communicating part for communicating the upper space with the lower chamber; and a float body disposed inside the lower chamber for floating to block the communicating part from the lower chamber when fuel flows into the lower chamber. A space between an inner surface of the lower chamber and an outer surface of the float body becomes a flow channel for gas when the float body is in a lower position. A distance between the outer surface of the float body and the inner surface of the lower chamber is not uniform in a circumferential direction of the float body. A portion having a large distance functions as a main flow channel for gas.

Abstract: A fuel vapor emission system for small engine gas tank which does not require redesign or retooling for manufacturing of the tank. A new filler tube has the lower end positioned to cause fuel to rise rapidly in the tube before the tank is full, signaling the operator to stop refueling and maintain a vapor dome in the tank when the filler cap is replaced. A vapor vent valve is disposed in a separate access opening and includes a float operated rollover valve. The vent valve opens when a predetermined positive pressure is reached in the tank; and, a reverse flow vacuum relief valve is disposed in the vent valve. The outlet of the vent valve is intended to be connected to either a storage canister or the engine air inlet.

Abstract: A canister includes a casing that has a tank port connected to a fuel tank, an atmospheric port connected to an atmospheric passage communicating with atmosphere, and a purge port connected to an intake passage of an engine. An adsorbent is charged in the casing for adsorbing fuel vapor. A support member defines an accommodation chamber in the casing. The support member supports the adsorbent. A pump is supported by the support member. The pump is accommodated in the accommodation chamber. The pump introduces atmospheric air into the accommodation chamber through the atmospheric passage. A motor is accommodated in the accommodation chamber. The motor drives the pump. A damping member is located between the pump and the support member for absorbing sound and vibration transmitted from the pump to the support member.

Abstract: A device combines a fuel control valve in a hollow can and a carbon canister, which can be further combined with a fuel tank. The device has a first chamber for preventing draining fuel and a second chamber containing active carbon. The first chamber is formed with a gas tube which is connected to the fuel tank and a gas channel connected to the second chamber. The second chamber is formed with a gas return tube. As such, the device combining the fuel control valve and the carbon canister is constructed. The hollow can is assembled to a lateral wall of the fuel tank and the gas tube can be connect with the fuel tank to form an integral structure.

Abstract: A device combining a two-way valve and a carbon canister includes a hollow can, which can be further combined with a fuel tank. The device has a first chamber for regulating inner pressure of the fuel tank and a second chamber containing active carbon. The first chamber is installed with a gas tube which is connected to the fuel tank and a gas channel connected to the second chamber. The second chamber is installed with a gas return tube so as to form the device combining the two-way valve and the carbon canister. The hollow can is assembled to a lateral wall of the fuel tank and the gas tube can be embedded into the fuel tank to form an integral structure.

Abstract: A low-resistance hydrocarbon-adsorptive cartridge for an air intake of an internal combustion engine comprising a structure for being mounted into a portion of an engine air intake system. The structure is adapted to orient and retain one or more thin sheets of activated carbon sheeting in the intake system. Preferably, a plurality of sheets is oriented such that the leading edge of each sheet is presented to the engine intake air stream, thereby minimizing reduction in total cross-sectional area of the intake system. Preferably, the one or more sheets are spaced apart by a distance that is small relative to the extent of the elements in the direction of engine air flow such that a high probability is created that hydrocarbons migrating out of a shut down engine's intake manifold will encounter a surface of at least one of the adsorptive sheets and thus be adsorbed.

Abstract: A hydrocarbon adsorber system in accordance with the invention comprising a carbon adsorber element installed in a throttle body of an internal combustion engine. The element may be installed on a wall or in a groove in the wall of the throttle throat at a location immediately upstream (outside) the throttle blade in the air flow direction, and/or an element may be installed on the downstream surface of the throttle blade itself. When an engine is shut down, the engine throttle normally remains slightly open. Any hydrocarbon emissions must pass through this slight opening, and applying carbon adsorbers to these locations takes advantage of proximity to such an opening, as any hydrocarbon emissions must pass close by the carbon adsorbers and thus have a much-increased probability of being adsorbed, in comparison with prior art more general carbon adsorption sites.

Abstract: A fuel tank assembly for small engines having a vapor storage canister disposed within the tank in the vapor dome with an atmospheric vent line to the canister through the tank wall and a canister vapor outlet line also through the tank wall. A fuel vapor vent valve is disposed in the vapor dome of the tank with the vent valve outlet connected to the canister inlet. A fuel filler tube extends through the tank wall to a desired depth to prevent vapor from escaping through the filler tube when the fuel level rises to the lower end of the filler tube and alerts the operator by rapid rise of fuel in the filler tube.

Abstract: A loose or missing fuel cap detection method for an evaporative emission control system of an automotive vehicle detects a loose or missing fuel cap based in part on whether fuel level changed. The method determines whether the fuel level changed, which is indicative of a refueling event. The method then determines if one or more leaks are present. If the fuel level changed and one or more leaks are present, the method determines that the fuel cap is loose or missing.

Abstract: An evaporative emissions filter for an engine air induction system. The evaporative emissions filter includes a hydrocarbon vapor-adsorbent member disposed within the air induction system. A mechanism is provided for mounting the evaporative emissions filter within the air induction system. Hydrocarbon vapors present in the air induction system after engine shut-down are substantially retained in the adsorbent member until air flows through the air induction system after the engine starts.

Abstract: A fuel container for a marine propulsion system is provided with a pump and a hose connected to an outlet of the pump and disposed within the cavity of the fuel container. The hose is provided with an opening, formed through its wall, through which a fluid can flow under certain circumstances. The opening is disposed in an ullage within the container and allows gaseous elements to be purged from the container when flow is induced from the container back to a fuel reservoir.

Abstract: A fuel vapor adsorbing device (10, 60, 70, 70?, 80) for adsorbing residual fuel vapors that remain in an intake conduit (1, 2, 3, 4) of an induction system of an internal combustion engine when the internal combustion engine is stopped may include an adsorbing member (40, 40?) that is constructed to adsorb the residual fuel vapors and is disposed along an inner wall surface of the intake conduit. The adsorbing member is arranged and constructed to form a supplemental intake path (T, T?, T??) between the adsorbing member and the inner wall surface of the intake conduit, so that intake air of the engine can flow through the supplemental intake path.

Abstract: In one aspect of the present invention, a hydrocarbon trapping device is provided, including a conduit and an adsorbing element positioned within the conduit. The conduit includes a wall having a wall thickness and the adsorbing element has an adsorbing element thickness that is generally equal to or less than the wall thickness. Furthermore, the adsorbing element defines a leading edge, a trailing edge, and a flow path extending between the leading and trailing edges in a direction substantially parallel to a longitudinal axis of the conduit.

Abstract: An emissions control canister including an insert tube and a final scrubber inside the tube. Because a scrubber formed as a carbon monolith is relatively fragile and easily damaged, a flexible, porous, resilient sling is provided for installing and retaining scrubber within cylindrical tube in lieu of either seals or elastomeric gaskets. An end of the scrubber is placed on a center portion of the sling, and the straps are folded alongside the cylindrical surface of the scrubber to form a sub-assembly. The sling is die-cut from planar stock of either a loose, thick, woven polyester fabric or an open-cell resilient foam. Advantages of the sling over a resilient elastomeric gasket are cost, ease of assembly, and the outer surface of the scrubber is made available as additional vapor adsorption area.

Abstract: A failure diagnosis apparatus for diagnosing a failure of an evaporative fuel processing system wherein a pressure in the evaporative fuel processing system is detected, and a purge control valve and a vent shut valve are closed when stoppage of the engine is detected. A determination is made as to whether there is a leak in the evaporative fuel processing system based on the detected pressure during a predetermined determination period after closing of the purge control and vent shut valves. The determination result is decided according to a parameter indicative of an amount of evaporative fuel generated in the fuel tank after stoppage of the engine.

Abstract: A fuel delivery module assembly for a vehicle which includes a fuel delivery module for supplying fuel from a fuel tank, a flange for attachment to a fuel tank and an emissions canister for controlling evaporative emissions. The fuel delivery module includes a reservoir for retaining fuel and a fuel pump for supplying fuel from the reservoir. The emissions canister is coupled to the fuel delivery module in a sliding relationship and is arranged such that the emissions canister can be displaced along a slide axis relative to the fuel delivery module between an installed position, in which the reservoir and emissions canister overlap parallel with the slide axis, and an installation position, in which the reservoir and emissions canister substantially do not overlap parallel with the slide axis. The invention also provides a fuel tank assembly comprising such a fuel delivery module assembly and to a method of positioning such a fuel delivery module assembly within a fuel tank.

Abstract: A stationary fuel storage system that includes a stationary fuel tank that defines a tank volume adapted to store a quantity of fuel. An evaporative emission device is disposed outside of the tank volume and defines a device volume that is in fluid communication with the atmosphere. A mass of fuel vapor adsorbing material is disposed within the device volume and a vent conduit provides fluid communication between the fuel tank and the evaporative emission device.

Abstract: In a canister system of seal type, a purge VSV is closed even if a predetermined purge condition is established so as to prevent direct purging of an evaporated fuel within a fuel tank into an intake system of an engine when one of the following conditions is established, that is, (1) a motor pump of an OBD pump module is driven; (2) a switching valve of the OBD pump module is set to ON; and (3) a closing valve is opened.

Abstract: A fuel pump module and carbon canister assembly adapted for mounting within a fuel tank. A fuel pump module has a flange and a body carried by the flange. A carbon canister is attached to the body of the fuel pump module and is adapted for an inclined orientation with respect to the flange of the fuel pump module. The fuel tank may include a bottom and a top having an opening through which the fuel pump module and carbon canister assembly may be inserted. The carbon canister may be adapted for resting on the bottom of the fuel tank once inserted therein.

Abstract: A fuel vapor treatment device for suppressing emission of fuel vapor from a fuel tank or the like of an automotive vehicle. The fuel vapor treatment device comprises a casing having a charge port connected to a fuel tank, a purge port connected to an intake section of an engine, and an atmospheric air port through which atmospheric air is introduced. Fuel vapor adsorbing material is filled in the casing. Additionally, an adsorbing material cartridge is disposed in a part of the casing and includes a cylindrical cartridge main body section having a cross-sectional area smaller than that of the casing. Fuel vapor adsorbing material is filled in the cartridge main body section. Air introduced from the atmospheric air port is flowable through the inside of the cartridge main body section to the fuel vapor adsorbing material in the casing.

Abstract: An integrated pressure management apparatus, system and method for minimizing resonance of a poppet. A housing defines a fluid communication passage between ports. The housing includes a first portion, which extends along an axis, and has a first surface parallel to the axis. A poppet is movable between a first configuration that prevents fluid communication between the ports, and a second configuration that permits fluid communication between the ports. The poppet includes a second portion. The second portion is translatable along the axis relative to the housing, and includes a tubular stem that has a second surface parallel to the axis. The second portion nests with the first portion so as to define a gap between the first and second surfaces. The first and second portions define a chamber, and the gap restricts fluid flow between the fluid communication passage and the chamber.

Abstract: Method and system of purging evaporative emission control canister using heated purge air comprises a scrubber containing an activated carbon fiber material or carbon monolith selected to adsorb butane and/or pentane isomer vapors in low concentrations in air passing through the scrubber and to desorb the adsorbed butane and/or pentane isomers when purged with exhaust heated purge air. A method for reducing bleed emission to almost zero mg per day uses exhaust heated air purging of the scrubber.

Abstract: Isolation valves of the invention are advantageously mechanically actuated. Such valves and associated methods comprise a first port in fluid communication with a first component; a second port in fluid communication with a second component; a third port in fluid communication with a third component; a diaphragm disposed within the valve for closing a normally open internal pathway to occlude fluid communication between the first port and the second port in response to a pressure differential across the diaphragm; and a flow sensitive pressure device for controlling the pressure differential across the diaphragm. Fluid flows from the second component to the third component upon closing of the normally open internal pathway. In an exemplary embodiment, isolation valves and methods of the invention are adapted for use in fuel tank emission control systems.

Abstract: A canister communicates with an intake manifold of an internal combustion engine through a purge pipe. The canister absorbs fuel vapor evaporated in a fuel tank. The absorbed fuel vapor is purged into the intake manifold when the engine is on. A gas leak check module communicates with the canister for drawing air by an air suction pump 43. When the engine is off, the air suction pump is driven and draws hydrocarbon floating at a vicinity of an intake port through the purge pipe. Thus, the hydrocarbon floating at the vicinity of the intake port is absorbed in the canister so that emission of hydrocarbon is reduced.

Abstract: A general-purpose engine includes a canister which adsorbs fuel vapor that has evaporated within a fuel tank. The fuel vapor is desorbed from the canister and guided to an intake system communicating with an engine main body. The engine main body includes a crankcase and a cylinder block joined to the crankcase to have an upwardly inclined cylinder axis (C). The canister is disposed to one side of the crankcase and beneath the cylinder block to avoid any increase in the dimensions of the general-purpose engine.

Abstract: The present invention relates to a gas filtering and recirculating device for a general machine having an engine and a fuel tank provided above the engine, which is mountable above the fuel tank and comprises at its one end an air outlet in fluid communication with atmosphere and an oil drain below the air outlet and above the fuel tank such that the oil drain is proximate the fuel tank, enabling the gas filtering and recirculating device to completely filter and absorb gas generated by fuel in the fuel tank and prevent the gas from discharging into the atmosphere via an air outlet in the fuel tank and causing air pollution.

Abstract: A motor and a pump in an air pump pressurizing a fuel vapor passage of a fuel vapor purge system, are disposed in a case which is partitioned into a chamber accommodating the motor and a chamber accommodating the pump, to transmit a driving force of the motor to the pump by a magnetic coupling.

Abstract: A fuel tank for an engine that includes an air cleaner assembly and an air-fuel mixing device. The fuel tank includes a first tank portion, a second tank portion connected to the first tank portion to define a fuel chamber, and a canister at least partially formed as part of the first tank portion. A first flow path is at least partially formed as part of the first tank portion. The first flow path provides fluid communication between the fuel chamber and the canister. A second flow path is at least partially formed as part of the first tank portion to provide fluid communication between the canister and at least one of the air-fuel mixing device and the air cleaner assembly.

Abstract: A fuel vapor leak detecting apparatus, includes: a valve which is in a vapor purge system including a canister that is communicated with a fuel tank and an internal combustion engine, and which controllably closes the vapor purge system; a pressurizing section which introduces atmospheric air into the vapor purge system to pressurize the vapor purge system; and an internal-pressure measuring section which detects an internal pressure of the vapor purge system. The pressurizing section supplies the air for a predetermined time in a state where the vapor purge system is closed. When the internal pressure measured by the internal-pressure measuring section at the air supply is equal to or lower than a preset criterion pressure, it is judged that leak occurs.

Abstract: A system is described using a fuel quality sensor or an estimate of fuel volatility for controlling various aspects of engine operation. For example, improved fuel tank leak detection may be achieved using an estimate of fuel volatility obtained from fuel purging operation.

Abstract: An evaporative emission control system for a hybrid vehicle comprises a scrubber containing an activated carbon fiber material selected to adsorb butane and/or pentane isomer vapors in low concentrations in air passing through the scrubber and apparatus for resistive heating of the activated carbon fiber material to help desorb the adsorbed butane and/or pentane isomers during a period when the internal combustion engine is operating for combustion of the desorbed vapor in the engine. The fibers are conductive and heat by resistive heating when electric current is passed through the fibers by the apparatus.

Abstract: An emissions control canister including an insert having an elongate well and flange. The insert extends into a chamber such that a carbon adsorption column is a hollow cylinder around the insert. After vapors flow through the column of adsorbent, flow is directed through holes in the flange and out through an atmosphere port. The flow path through the hollow cylinder has an increased L/D ratio and improves emission performance. In a second embodiment, a cylindrical tube surrounds the exit port and extends into the insert, forcing vapor flow along a tortuous path between the cylindrical wall and the insert. In a third embodiment, a final scrubber is added inside the tube.

Abstract: An evaporative emission control and leak detection system for a motor vehicle is provided. The system is in fluid communication with a fuel tank, an engine, and a carbon canister and includes an integrated valve module that is in fluid communication with the carbon canister and the atmosphere. The module provides for venting of the system when exposed to predetermined high negative and positive pressure conditions. The module includes a switch mechanism that is operable to indicate when the system is in a low negative pressure condition. The module further includes a one-way high negative pressure valve and a one-way high positive pressure valve coupled to a fluid passage that bypasses the high negative pressure valve and the switch. The high negative and high positive pressure valves are positioned in a stacked arrangement along a common axis in the valve module.

Abstract: An evaporative emissions control system for small internal combustion engines. A control valve assembly includes a pair of control valves which are respectively associated with a fuel line and with a vent line which each connect the fuel tank and the carburetor of the engine. The control valve assembly is automatically operable responsive to the rotation of a rotatable member of the engine drive train, such as the crankshaft, camshaft, flywheel, governor assembly, or other rotatable member. In one embodiment, for example, the control valve assembly is driven from the flywheel. When the engine is not running, the flywheel is stationary and does not rotate, and the control valves automatically closes the vent line and the fuel line, thereby trapping fuel vapors within the fuel tank and blocking the supply of liquid fuel to the carburetor.

Abstract: An evaporative fuel adsorbent 32, which adsorbs evaporative fuel, is positioned substantially parallel to a sidewall surface 30 of a surge tank 22. A retention member 34 is positioned between the sidewall surface 22 and evaporative fuel adsorbent 32 to prevent oil, which runs down on the sidewall surface 22, from adhering to the evaporative fuel adsorbent 32. The evaporative fuel adsorbent 32 is mounted on the sidewall surface 30 of the surge tank 22 via the retention member 34.

Abstract: An apparatus and a method for managing fuel vapor pressure in a fuel system that supplies fuel to an internal combustion engine. The fuel vapor pressure management apparatus performs leak detection on a headspace of the fuel system, performs excess negative pressure relief of the headspace, performs excess positive pressure relief of the headspace, and performs a diagnostic on the purge valve. The apparatus includes a housing, a pressure operable device, and a printed circuit board. The housing defines an interior chamber. The pressure operable device separates the interior chamber into first and second portions. And the pressure operable device includes a poppet that moves along an axis and a seal that is adapted to cooperatively engage the poppet. The printed circuit board is supported by the housing in the interior chamber.

Abstract: A fuel/air separation apparatus for separating air and/or vapor from a liquid fuel. The apparatus includes a canister and filter element which separates the entrained air and/or vapor from the fuel and provides substantially air/vapor-free fuel for use by an engine and returns the filtered air/vapor and any excess fuel to the vehicle's fuel tank.

Abstract: A fuel vapor separator includes a polymeric body that preferably has a polymeric canister and a polymeric lid secured to the canister to define a liquid tight enclosure. The enclosure is preferably divided into at least two chambers. One chamber preferably receives liquid fuel and communicates with a heat exchanger to cool the supply of liquid fuel therein. Vapor is trapped in a vapor dome area above the liquid fuel and is vented through a vent valve carried by the fuel vapor separator. The other chamber of the enclosure preferably receives a high pressure fuel pump adapted to receive liquid fuel from the first chamber, and to deliver liquid fuel under pressure to the engine. Preferably, the chamber in which the fuel pump is received is communicated with a coolant to facilitate cooling the fuel pump in use.

Abstract: A fuel system and a method of method of managing fuel vapor pressure in the fuel system. The fuel system a fuel tank having a headspace, a fuel vapor collection canister in fluid communication with the headspace, a purge valve, and a fuel vapor pressure management apparatus. The method includes performing leak detection on the headspace, and preventing a flow of fluid through an elastic diaphragm during leak detection. The elastic diaphragm includes at least one opening through which passes the flow of fluid. And the preventing the flow of fluid includes a first portion of the elastic diaphragm sealingly engaging a second portion of the elastic diaphragm. The method further includes relieving excess negative pressure in the headspace and relieving excess positive pressure in the headspace by fluid flow in different directions along the same flow path that includes the opening in the diaphragm.

Abstract: A method determines the fuel vapor pressure in a fuel tank system of a motor vehicle. The fuel tank system includes a tank venting system and the fuel vapor pressure is determined from a temperature dependency of at least a characteristic variable of the tank venting system correlating indirectly to the inner pressure present in the fuel tank system.

Abstract: An evaporative fuel control system for an internal combustion engine having a canister that absorbs evaporative fuel generated in the fuel tank. An atmosphere open passage connects the canister with the atmosphere. A purge valve is disposed between the intake passage and the canister. A purge controller controls the purge valve so that the evaporative fuel absorbed by the canister is purged and supplied to the intake passage. A leak check system examines leakage in the evaporative fuel control system by causing negative pressure in the evaporative fuel control system during stop of the engine. The leak check system includes a factory test mode which is provided with a decreased leak check time which is shorter than that for normal leak check when the evaporative fuel control system receives a factory test signal.

Abstract: An apparatus for detecting fuel-vapor gas leaks that includes a jet pump (8) that introduces outside air into and pressurizes a vapor purge system including a fuel tank (1) by gasoline flow from a fuel pump (2); an internal pressure sensor (14) for measuring vapor purge system internal pressure, an open/close controllable reference orifice (21) that causes leakage through a reference leak hole; and a storage device for storing as an initial curve pressure changes during pressurization by the jet pump (8) for a predetermined time period, with the reference orifice (21) alone opened. The device can accurately detect leakage even while an internal combustion engine is running because it judges leak presence/absence by comparing a time series in a pressure curve obtained by jet pump (8) pressurization over the predetermined time period while idling with the vapor purge system completely shut-off, with a time series in the initial curve.

Abstract: An internal combustion engine is provided with a variable valve train capable of altering opening and closing timings and/or opening amounts of at least one of an intake valve and an exhaust valve of an internal combustion engine. The internal combustion engine is characterized in that the internal combustion engine is further provided with a negative pressure mechanism that operates using intake pipe negative pressure generated in an intake passage of the internal combustion engine, a throttle valve for adjusting the flow rate of intake air flowing through the intake passage, and negative pressure generating device that controls at least one of the variable valve train and the throttle valve to generate the intake pipe negative pressure, when the intake pipe negative pressure for operation of the negative pressure mechanism is insufficient.