CHARGE FORMATION DEVICE WITH ELECTRICALLY OPERATED VAPOR SEPARATOR VENT VALVE

Abstract

A charge formation device (10) for an internal combustion engine (12), comprising:a housing having an inlet chamber (100) in which a supply of fuel is received, a vent passage (102) communicating with the inlet chamber (100), and a throttle bore (20) having an inlet through which air is received;a throttle valve (52) carried by the housing and having a valve head (54) movable relative to the throttle bore (20) to control a flow of fluid through the throttle bore (20);anda vent valve (130) carried by the housing and having a valve element (132) movable between an open position in which fluid can flow from the inlet chamber (100) through the vent passage (102) and a closed position in which fluid is inhibited or prevented from flowing from the inlet chamber (100) through the vent passage (102), the vent valve (130) being electrically actuated, the vent valve (130) being actuated as a function of a pressure within the inlet chamber.;

Description

TECHNICAL FIELDThe present disclosure relates generally to a charge forming apparatus for supplying fuel and air to an engine, and more particularly to a charge forming apparatus having an electrically actuated vapor separator vent valve.BACKGROUNDFor supplying an air-fuel mixture to an internal combustion engine to aid in its operation, a variety of configurations of fuel injection restrictors are known in which gasoline is injected into a main bore at a relatively high pressure, typically in the range of 6 to 40 psi and sometimes up to 80 psi or more above ambient atmospheric pressure or 21 to 55 psia (psi absolute) or more to facilitate mixing or dispersing the liquid fuel in the air-fuel mixture supplied to the engine. A fuel pump and a pressure regulator supply liquid fuel under this high pressure to a fuel metering valve or injector which is opened and closed by an electronic controller at fixed times to deliver the appropriate amount of fuel into the main bore for the current operating condition of the engine. Typically, the fuel injector is located upstream of a throttle head or much further downstream of the throttle body and near the engine fuel inlet or intake valve pocket.DE 10 2009 060 973 A1 discloses a hand-held working device having an internal combustion engine and an ignition, which is equipped with a starting device for the internal combustion engine. The starting device comprises an electric motor and a battery is provided for driving the electric motor, which battery is connected to the latter via a switching device. To simplify the arrangement and reliable handling, a common operating element for switching on the ignition and activating the starting device is present, which can be adjusted at least into a stop position, an operating position and a starting position, wherein the operating position lies between the stop position and the starting position. Thus, this document describes a fuel system comprising a fuel tank having a vent outlet, a throttle body assembly having a vent passage, a vent valve, and an electrically actuated fuel metering valve.An apparatus for preventing fuel evaporation is described in U.S. Pat. No. 3,548,797. The device prevents evaporating fuel from a fuel tank and a carburetor of a motor vehicle from entering into the atmosphere and contaminating it. The apparatus includes a fuel vapor absorption tank connected to a fuel chamber of the carburetor via a pressure regulating valve, the pressure regulating valve being integrally integrated with the carburetor. Thereby, the length of the breather tube is shorter than that of a conventional apparatus of this kind, and an adverse effect which would otherwise affect the fuel flow characteristics of the carburetor can be minimized. Thus, this document also discloses a fuel system comprising a fuel tank having a vent outlet, a throttle body assembly having a vent passage, and a vent valve.DE 38 14 825 A1 finally describes a circuit arrangement for an electric ventilation changeover valve. Known circuit arrangements switch the float chamber venting from internal to external venting in order to solve hot problems of the internal combustion engine, for example as a function of the fuel supply pressure. However, these designs are unsatisfactory because they do not solve the hot problem occurring during engine operation. The circuit arrangement described in this document is distinguished in that at relatively high temperatures in the float chamber region a specific period of time is switched to external ventilation. Such circuit arrangements are used in automotive construction. Thus, this document describes a charge forming apparatus having a housing, a throttle valve and an electrically operated bleed valve.SUMMARYThe present invention discloses a charge forming device according to independent claim 1 and a fuel system according to independent claim 13.According to the present invention, a charge forming apparatus for an internal combustion engine includes a housing, a throttle valve, and a bleed valve. The housing includes an inlet chamber in which a fuel supply is received, a vent passage communicating with the inlet chamber, and a throttle bore having an inlet through which air is received. The throttle valve is supported by the housing and has a valve head movable relative to the throttle bore to control fluid flow through the throttle bore. And the vent valve is electrically actuated, is supported by the housing, and includes a valve member movable between an open position in which fluid can flow from the inlet chamber through the vent passage and a closed position in which fluid is prevented or inhibited from flowing from the inlet chamber through the vent passage. The vent valve is actuated as a function of a pressure within the inlet chamber.In at least some implementations, the housing includes a body and a cover connected to the body, and the vent passage is at least partially formed in the cover and the vent valve is supported by the cover. The vent valve is operated so as to maintain a pressure between 0.34 mmHg and 19 mmHg.In at least some implementations, an electrically actuated fuel metering valve is supported by the housing and has an inlet connected to the inlet chamber for receiving fuel from the inlet chamber and an outlet connected to the throttle bore and through which fuel is supplied into the throttle bore. Actuation of both the fuel metering valve and the bleed valve may be controlled by a single controller, and the controller may be supported by the housing. The throttle valve may be electrically actuated, and actuation of both the fuel metering valve and the throttle valve may be controlled by a single controller. In at least some implementations, actuation of each of the fuel metering valve, the throttle valve, and the bleed valve is controlled by a single controller.In at least some implementations, an inlet valve is supported by the housing and includes a valve that controls fuel flow into the inlet chamber. The inlet valve may be connected to a float received in the inlet chamber that actuates the inlet valve as a function of the fuel level within the inlet chamber. A second venting passage may be provided for supplying gaseous materials from a second source, such as a fuel tank, to the inlet chamber, wherein a flow of the gaseous materials from the inlet chamber and from the second source is controlled by the venting valve.According to the invention, a fuel system includes a fuel tank, a throttle body assembly, and a vent valve. The fuel tank includes a fuel outlet and a vent outlet. The throttle body assembly includes an inlet chamber communicating with the fuel outlet to receive fuel from the tank and the vent outlet to receive gaseous materials from the tank into the inlet chamber. The throttle body assembly also includes a vent passage from which gases can be discharged from the inlet chamber. The vent valve is supported by the throttle body assembly to control venting of the inlet chamber and fuel tank.In at least some implementations, a float is received within the inlet chamber and an inlet valve is connected to the float such that the inlet valve is actuated by the float as a function of the fuel level within the inlet chamber.According to the invention, the throttle body comprises a throttle bore having an inlet through which air is received, and an electrically actuated fuel metering valve is supported by the housing and has an inlet connected to the inlet chamber for receiving fuel from the inlet chamber and an outlet connected to the throttle bore through which fuel is supplied into the throttle bore. Actuation of both the fuel metering valve and the bleed valve may be controlled by a single controller.In at least some implementations, a second venting passage directs gaseous materials from a second source to the inlet chamber, and the flow of gaseous materials from the inlet chamber and from the second source is controlled using the venting valve. The vent valve may be operated as a function of pressure within the inlet chamber so as to maintain a pressure between 0.34 mmHg and 19 mmHg.BRIEF DESCRIPTION OF THE DRAWINGSThe following detailed description of certain embodiments and the best mode of operation is set forth with reference to the accompanying drawings, in which: FIG. 1 is a perspective view of a throttle body assembly with an electrically actuated vent valve; FIG. 2 is a perspective view of the throttle body assembly; FIG. 3 is a cross-sectional view of the throttle body assembly illustrating an intake valve and a fuel metering valve; FIG. 4 is a perspective and partial sectional view of a cover, an intake valve, and a vent valve of the throttle body assembly; FIG. 5 is a fragmentary perspective sectional view of a cover and a vent valve supported by the cover; and FIG. 6 is a schematic view of a fuel system including a fuel tank, a throttle body assembly, and an engine.DETAILED DESCRIPTIONReferring now to the drawings in detail, Figures 1-3 illustrate a charge forming apparatus 10 which supplies a combustible fuel-air mixture to an internal combustion engine 12 (shown schematically in Figure 1) to assist in the operation of the engine. The charge forming apparatus 10 may be used on a two or four stroke internal combustion engine and, at least in some implementations, includes a throttle body assembly 10 from which air and fuel are discharged for delivery to the engine.The assembly 10 includes a housing having a throttle body 18 having a throttle bore 20 with an inlet (not shown) through which air enters the throttle bore 20 and an outlet 24 connected to or otherwise communicating with the engine (e.g., an intake manifold 26 thereof). The inlet may receive air from an air filter (not shown), if desired, and that air may be mixed with fuel supplied by a fuel metering valve 28 carried by or in communication with the throttle body 18. The intake manifold 26 generally communicates with a combustion chamber or cylinder of the engine during successive periods of a piston cycle. In a four stroke engine application, as shown, the fluid may flow through an intake valve and directly into the piston cylinder. Alternatively, in a two stroke engine application, air typically flows through the crankcase (not shown) before entering the combustion chamber region of the piston cylinder through a port in the cylinder wall that is intermittently opened by the reciprocating engine piston.The orifice 20 may have any desired shape, including (but not limited to) a constant diameter cylinder or venturi shape (FIG. 5 ), wherein the inlet results in a tapered or conical converging region that results in a reduced diameter neck that results in a tapered or conical diverging region that results in the outlet 24. The converging region may increase the velocity of the air entering the throat and create or increase a pressure drop in the region of the throat. In at least some implementations, a secondary venturi, sometimes referred to as boost venturi 36, may be located within the throttle bore 20 regardless of whether or not the throttle bore 20 is a venturi shape. The boost venturi 36 may be of any desired shape and, as shown in FIGS. 1 and 3, has a converging inlet portion 38 leading to a reduced diameter intermediate throat 40 leading to a diverging outlet 42. The boost venturi 36 may be connected to the throttle body 18 within the throttle bore 20, and in some implementations, the throttle body may be molded from a suitable metal and the boost venturi 36 may be molded as part of the throttle body, in other words, from the same piece of material that is molded as a feature of the throttle body when the remainder of the throttle body is molded. The boost venturi 36 may also be an insert that is suitably connected to the throttle body 18 after the throttle body is formed. In the example shown, boost venturi 36 includes a wall 44 defining an internal passage 46 that is open to throttle bore 20 at both inlet 38 and outlet 42. A portion of the air flowing through the throttle body 18 flows into and through the boost venturi 36, increasing the velocity of that air and decreasing its pressure. The boost venturi 36 may have a central axis 48 (FIG. 3 ) that may be generally parallel to and radially offset from a central axis 50 (FIG. 3 ) of the throttle bore 20, or the boost venturi 36 may be oriented in any other suitable manner.Referring to FIG. 1, the air flow rate through the throttle bore 20 and into the engine is controlled at least partially by a throttle valve 52. In at least some implementations, the throttle valve 52 includes a head 54 that may include a flat plate disposed in the throttle bore 20 and connected to a rotating throttle valve shaft 56. The shaft 56 extends through a shaft bore 58 formed in the throttle body 18 that intersects and may be disposed generally perpendicular to the throttle bore 20. The throttle valve 52 may be driven or moved by an actuator 60 between an idle position, in which the head 54 substantially blocks air flow through the throttle bore 20, and a fully or widely opened position, in which the head 54 least limits air flow through the throttle bore 20. In one example, the actuator 60 may be an electrically-driven motor 62 connected to the throttle valve shaft 56 to rotate the shaft and thus rotate the valve head within the throttle bore 20. In another example, the actuator 60 may include a mechanical connection, such as a lever attached to the throttle valve shaft 56, to which a Bowden cable may be connected to manually rotate the shaft 56 as desired and as known in the art.The fuel metering valve 28 (FIG. 3 ) may include an inlet 66 to which fuel is supplied, a valve element 68 (e.g., a valve head) that controls the fuel flow rate, and an outlet 70 downstream of the valve element 68. To control the actuation and movement of the valve element 68, the fuel metering valve 28 may include or be connected to an electrically driven actuator 72, such as (but not limited to) a solenoid. Among other things, the solenoid 72 may include an outer housing 74 received in a cavity 76 in the throttle body 18, a coil 78 wound around a spool 80 received within the housing 74, an electrical connector 82 arranged to be connected to a power source to selectively energize the coil 78, and an armature 84 slidably received within the spool 80 for reciprocation between the extended and retracted positions. The valve element 68 may be supported by the armature 84 or otherwise moved relative to a valve seat 86 that may be defined in the solenoid 72 and / or the throttle body 18. When the armature 84 is in its retracted or retracted position, the valve member 68 is spaced from the valve seat 86 and fuel can flow through the valve seat. When the armature 84 is in its extended position, the valve member 68 may be closed against or seated against the valve seat 86 to inhibit or prevent fuel flow through the valve seat. The solenoid 72 may be constructed in accordance with U.S. patent application US 2016 / 0123489 A1. The inlet 68 may be centrally or generally coaxial with the valve seat 86, and the outlet 70 may be spaced radially outward from the inlet and oriented generally radially outward. Of course, other metering valves, including but not limited to other solenoid valves or commercially available fuel injectors, may be used instead, if desired in a particular application.In the example shown, the valve seat 86 is defined within the cavity 76 of the throttle body 18 and may be defined by a feature of the throttle body or by a component inserted into and supported by the throttle body or housing 74 of the solenoid. Also, in the example shown, the valve seat 86 is defined by a metering nozzle 88 supported by the throttle body 18. The nozzle 88 may be a separate body that is press fit or otherwise installed into the cavity 76 and has a passage or orifice 90 through which fuel at the inlet 66 flows to the metering valve 28 before reaching the valve seat 86 and the valve member 68. The flow area of the passages downstream of the nozzle 88 may be greater than the minimum flow area of the nozzle so that the nozzle provides the greatest restriction on fuel flow through the metering valve 28. Instead of or in addition to the nozzle 88, a passage of suitable size may be drilled or otherwise formed into the throttle body 18 to define a maximum restriction on fuel flow through the metering valve 28. The use of a nozzle 88 may facilitate the use of a general multiple engine throttle body design or in various engine applications where different fuel flow rates may be required. To achieve the different flow rates, different nozzles with orifices having different effective flow areas may be inserted into the throttle bodies, while the remainder of the throttle body may be the same. Additionally, passages of different diameters may be formed in the throttle body 18 in addition to or instead of using a nozzle 88 to achieve the like.Fuel flowing through the valve seat 86 (e.g., when the valve element 68 is moved away from the valve seat by retracting the armature 84) flows to the metering valve outlet 70 for delivery into the throttle bore 20. In implementations where the boost venturi 36 is spaced from the outlet 70, an outlet pipe 92 (FIG. 3 ) may extend from a passage or port defining at least a portion of the outlet 70 and through an opening 94 in the boost venturi wall 44 to communicate with the boost venturi passage 46. The tube 92 may extend into and communicate with the throat 40 of the boost venturi 36, wherein a negative or subatmospheric pressure signal may be of greatest magnitude and the velocity of air flowing through the boost venturi 36 may be highest. Of course, the tube 92 may open to another region of the boost venturi 36 if desired. Further, the tube 92 may extend through the wall 44 such that an end of the tube may extend into the passageway 46 of the boost venturi, or the tube may extend through the passageway of the boost venturi such that an end of the tube intersects the opposing wall of the boost venturi, and may include holes, slots, or other features through which fuel may flow into the passageway 46 of the boost venturi, or the end of the tube may be recessed within or spaced apart from (i.e., not protruding into) the passageway within the opening 94.Fuel may be supplied from a fuel source to the inlet 66 of the metering valve and, when the valve member 68 is not closed on the valve seat 86, fuel may flow through the valve seat and metering valve outlet 70 and to the throttle bore 20 to be mixed with the air flowing therethrough and supplied as a fuel-air mixture to the engine. The fuel source may provide fuel to the metering valve 28 at a desired pressure. In at least some implementations, the pressure may be ambient pressure or a pressure slightly above atmospheric pressure up to about 6 psi above ambient pressure.To supply fuel to the metering valve inlet 66, the throttle body assembly 10 may include an inlet chamber 100 (FIG. 3 ) into which fuel is received from a fuel supply, e.g., a fuel tank. The throttle body assembly 10 may include a fuel inlet 104 leading to the inlet chamber 100. In a system where fuel pressure is generally at atmospheric pressure, the fuel flow may be directed into the inlet chamber 100 under the action of gravity. In at least some implementations, as shown in FIGS. 3 and 4, a valve assembly 106 may control the flow of fuel into the inlet chamber 100. The valve assembly 106 may include a valve element 108 and may include or be in communication with a valve seat 110 such that a portion of the valve element 108 is selectively engageable with the valve seat 110 to inhibit or prevent fluid flow through the valve seat, as will be described in more detail below. The valve element 108 may be connected to an actuator 112 that moves the valve 108 relative to the valve seat 110, as will be described in more detail below. A vent port or passage 102 (FIGS. 4 and 5 ) may be connected to the intake chamber and to the engine intake manifold or other desired location as long as the desired pressure is reached in the intake chamber 100 during operation, which may also include atmospheric pressure. The fuel level within the inlet chamber 100 provides a head or pressure of the fuel that may flow through the metering valve 28 when the metering valve is open.To maintain a desired fuel level in the inlet chamber 100, the valve 108 is moved relative to the valve seat 110 by the actuator 112, which in the example shown comprises a float or is defined by a float that is received in the inlet chamber and responds to the fuel level in the inlet chamber. The float 112 may float in fuel and provide a lever 117 pivotally connected to the throttle body 18 or a cover 118 connected to the body 18 via a pin 119, and the valve 108 may be connected to the float 112 for movement as the float moves in response to changes in fuel level in the inlet chamber 100. When a desired maximum fuel level is present in the inlet chamber 100, the float 112 has been moved to a position in the inlet chamber in which the valve 108 engages and is closed against the valve seat 110, closing the fuel inlet 104 and preventing further fuel flow into the inlet chamber 100. When fuel is discharged from the inlet chamber 100 (e.g., to the throttle bore 20 through the metering valve 28), the float 112 moves in response to the lower fuel level in the inlet chamber and thereby moves the valve 108 away from the valve seat 110 such that the fuel inlet 104 is again open. When the fuel inlet 104 is open, additional fuel flows into the inlet chamber 100 until a maximum level is reached and the fuel inlet 104 is closed again.The inlet chamber 100 may be at least partially defined by the throttle body 18, e.g., by a recess formed in the throttle body and a cavity 121 in the cover 118 supported by the throttle body and defining a portion of the housing of the throttle body assembly 10. An outlet 120 (FIG. 3 ) of the inlet chamber 100 leads to the inlet 66 of the metering valve. In order for fuel to be available at all times at the metering valve 28 when fuel is within the inlet chamber 100, the outlet 120 may be an open passage without any interposed valve, at least in some implementations. The outlet 120 may extend from the bottom or a lower portion of the inlet chamber so that fuel at atmospheric pressure may flow to the metering valve 28.In use of the throttle body assembly 10, fuel is maintained in the inlet chamber 100 as described above and thus in the outlet 120 and the metering valve inlet 66. When the metering valve 28 is closed, there is no or substantially no flow of fuel through the valve seat 86 and thus no flow of fuel to the metering valve outlet 70 or to the throttle bore 20. The timing and duration of opening and closing of the metering valve may be controlled by a suitable microprocessor or other controller. The timing of the fuel flow (e.g., injection) or when the metering valve 28 is opened during an engine cycle may alter the pressure signal at the outlet 70, and thus the differential pressure across the metering valve 28 and the resulting fuel flow rate into the throttle bore 20. In addition, both the strength of the engine pressure signal and the air flow rate through the throttle valve 52 vary significantly between the engine idling operation and the engine wide open throttle operation. Thus, the duration that the metering valve 28 is open at any given fuel flow rate affects the amount of fuel flowing into the throttle bore 20.The inlet chamber 100 may also serve to separate liquid fuel from gaseous fuel vapors and air. Liquid fuel precipitates to the bottom of the intake chamber 100, and the fuel vapor and air rise to the top or head end of the intake chamber where the fuel vapor and air can flow out of the intake chamber through the purge passage 102 or the purge outlet (and thus can be supplied into the intake manifold and then to a combustion chamber of the engine). To control venting of the gases from the inlet chamber 100, a vent valve 130 may be provided on the vent passage 102. The vent valve 130 may include a valve element 132 that is moved relative to a valve seat 134 to selectively allow fluid flow through the vent or vent passage 102. To allow further control of the flow through the vent passage 102, the vent valve 130 may be electrically actuated to move the valve element 132 between open and closed positions relative to the valve seat 134.As shown in FIGS. 4 and 5, the vent valve 130 may include or be connected to an electrically driven actuator such as (but not limited to) a solenoid 136 to control the actuation and movement of a valve element 132. Among other things, the solenoid 136 may include an outer housing 138 received in a cavity 140 within the throttle body 18 or the cover 118 and held therein by a retaining plate or body 141, a coil 142 wound around a spool 144 received within the housing 138, an electrical connector 146 arranged to be connectable to a power source to selectively energize the coil 142, an armature 148 slidably received within the spool 144 for reciprocation between extended and retracted positions, and an armature stop 149. The valve element 132 may be supported or otherwise moved by the armature 148 relative to a valve seat 134, which may be defined within one or more of the solenoid 136, the throttle body 18, and the cover 118. When the armature 148 is in its retracted position, the valve element 132 is spaced from the valve seat 134 and fuel can flow through the valve seat. When the armature 148 is in its extended position, the valve member 132 may be closed against or seated against the valve seat 134 to inhibit or prevent fuel flow through the valve seat. The solenoid 136 may be constructed in accordance with U.S. patent application US 2016 / 0123489 A1. An inlet 150 from the vent passage to the valve seat 134 may be centrally or generally coaxial with the valve seat 134, and an outlet 152 from the valve seat to the downstream portion of the vent passage 102 may be spaced radially outward from the inlet and oriented generally radially outward. Of course, other valves may be used instead, including but not limited to other solenoid valves (including but not limited to piezo-type solenoid valves) or other electrically actuated valves, if desired in a particular application.The venting passage 102 or outlet could be connected to a filter or vapor canister comprising an adsorbent material such as activated carbon to reduce hydrocarbons or remove them from the vapor. The vent passage 102 could also or instead be connected to an intake manifold of the engine where the vapor may be added to a combustible fuel-air mixture provided by the throttle bore 20. In this manner, steam and air flowing through the vent valve 130 are directed to a downstream component as desired. In the illustrated implementation, an exhaust passage 154 extends from the cover 118 downstream of the valve seat 134 and to an intake manifold of the engine. While the outlet passage 154 is at least partially defined in a conduit routed outside of the cover 118 and the throttle body 18, the outlet passage 154 could instead be at least partially defined by one or more bores or cavities formed in the throttle body and / or the cover, and / or by a combination of internal cavities / passages and an external conduit or conduits.In at least some implementations, the cover 118 defines a portion of the inlet chamber 100, and the vent passage 102 extends at least partially within the cover and communicates at a first end 156 with the inlet chamber 100 and at a second end 158 with an outlet 160 from the throttle body (e.g., the cover). The vent valve 130 and the valve seat 132 are disposed between the first 156 and second 158 ends of the vent passage 102 such that the vent valve controls flow through the vent passage. In the illustrated implementation, the vent passage 102 is entirely within the cover 118, and the vent valve 130 is supported by the cover, e.g., within the cavity 140 formed in the cover.In at least some implementations, a pressure in the vent passage 102 may interfere with the flow of fuel from the inlet chamber 100 to the fuel metering valve 28 and the throttle bore 20. For example, if the vent passage 102 is connected to the intake manifold or to an air cleaner box / filter, a subatmospheric pressure may prevail within the vent passage. The subatmospheric pressure, when in communication with the inlet chamber 100, may reduce the pressure within the inlet chamber and reduce the flow of fuel from the inlet chamber. Accordingly, closing the vent valve 130 may impede or prevent transmission of the subatmospheric pressure from the vent passage 102 to the inlet chamber 100. A pressure sensor responsive to the pressure in the vent passage 102 or, for example, in the intake manifold may provide a signal used to at least partially control the actuation of the vent valve 130 as a function of the sensed pressure to improve control of the pressure in the intake chamber. Additionally or instead, the vent valve 130 may be closed to allow some positive, superatmospheric pressure to be present in the inlet chamber 100, which may improve fuel flow from the inlet chamber to the throttle bore 20. And, the vent valve 130 may be opened to allow engine pressure pulses (e.g., from the intake manifold) to increase the pressure within the intake chamber 100. As mentioned above, the opening of the vent valve 130 can be timed with such pressure pulses via a pressure sensor or otherwise. These examples allow for better control of fuel flow from the intake chamber 100, and thus better control of the fuel-air mixture supplied from the throttle bore 20. In this manner, the vent valve 130 can be opened and closed at will to vent gases from the inlet chamber 100 and control the pressure within the inlet chamber.Moreover, it may be desirable to close the vent passage 102 to prevent the fuel in the inlet chamber 100 from aging (due to evaporation, oxidation, or otherwise) or becoming poor over time, such as during storage of the apparatus with which the throttle body assembly 10 is used. In this way, the vent valve 130 may be closed when the device is not used to reduce the likelihood or speed at which fuel in the throttle body assembly 10 ages or becomes poor.Finally, when the vent valve moves from open to closed, movement of the armature 148 and the valve element 132 displaces the air / vapors in the vent passage 102 toward and into the inlet chamber 100, which may increase the pressure in the inlet chamber. Repeated actuations of the vent valve 130 may then cause some, though relatively small, increase in pressure that facilitates fuel flow from the inlet chamber 130 to the throttle bore 20.In at least some implementations, pressure within the inlet chamber 100 may be controlled to a value between 0.34 mmHg and 19 mmHg by actuation of the vent valve 130. In at least some implementations, the vent valve 130 may be repeatedly opened and closed with a cycle time between 1.5 ms and 22 ms. And in at least some implementations, for example, the bleed valve 130 may be controlled at least when the throttle valve is at least 50% of the way between its idle position and its wide open position (e.g., between 50% and 100% of the angular rotation from idle to wide open), as the pressure of the intake manifold may be greater in this throttle position range and thus more likely to interfere with the pressure in the intake chamber.The vent valve 130 may be actuated by a controller 162 (FIG. 1 ) that controls when electrical power is supplied to the solenoid 136. The controller 162 may be the same controller that also actuates the fuel metering valve 28, or a separate controller. Additionally, the controller 162 that actuates the vent valve 130 and / or the fuel metering valve 28 may be attached to or otherwise supported by the throttle body assembly 10, or the controller may be located remotely from the throttle body assembly, as desired. In the example shown, the controller 162 is supported within a sub-housing 164 that is attached to or otherwise supported by the throttle body 18 and / or the cover 118 (e.g., the body and / or the cover), and that may include a printed circuit board 166 and a suitable microprocessor 168 or other controller for actuating the metering valve 28, the bleed valve 130, and / or the throttle valve (e.g., upon rotation by a motor 62, as shown and described above). Moreover, information from one or more sensors may be used to at least partially control the operation of the vent valve, and the sensor or sensors may be associated with the controller that controls the actuation of the vent valve.As shown in FIG. 6, a fuel system 200 may include a fuel tank 202, a throttle body assembly 10, and an engine 12 having an intake manifold 26. The fuel tank 202 may include an interior 204 in which a supply of liquid fuel 206 is maintained for delivery to the engine 12 via the throttle body assembly 10, as shown above. The liquid fuel may flow from the fuel tank 202 (under the action of gravity or via a pump) through a first conduit 208 into the inlet chamber 100 of the throttle body assembly 10. From the intake chamber 100, the liquid fuel in a fuel-air mixture may flow to the throttle bore 20 and from the throttle bore to the intake manifold 26 of the engine 12 (flow from the throttle bore to the intake manifold is schematically depicted as occurring through a conduit 210, but a conduit is not required when the throttle body 18 is attached to the intake manifold 26). The intake chamber 100 may be vented to the intake manifold 26 via a second conduit 212 and gaseous flow through the second conduit may be controlled by a valve 130, such as a solenoid valve, as described above.Further, an upper portion 214 of the fuel tank 202 includes air and fuel vapor above the level of the liquid fuel 206. This upper portion or vapor portion 214 of the fuel tank 202 may be communicated to the inlet chamber 100 via a third conduit 216 so that the fuel tank air or vapor (e.g., gaseous species) may be vented in the same manner as the inlet chamber 100, the gaseous flow also being controlled by the inlet chamber vent valve 130. Therefore, a single vent valve 130 may be used to control venting of gases from both the inlet chamber 100 of the throttle body assembly 10 and the fuel tank 202. In this way, an internal pressure within the tank 202 may be controlled, and this may be done without a separate vent valve carried by the fuel tank. Because a vent outlet 218 and conduit 216 may be closed by the inlet chamber vent valve 130, no fuel will leak from the fuel tank 202 via the vent or conduit when the fuel tank is turned upside down, for example. Therefore, this fuel system 200 does not require a costly and more complex rollover valve (i.e., a valve that closes the fuel tank vent outlet 218 when the fuel tank is turned upside down), as is commonly used when a separate vent valve is connected to the fuel tank.The vent valve 130 may be controlled in any desired manner to effect proper venting of both the inlet chamber 100 and the fuel tank 202, including the manner(s) described above. Other venting schemes may be used to facilitate filling fuel into the fuel tank, whereupon a refueling event is detected and the vent valve 130 is opened or reciprocated between open and closed positions to allow vapor and air to escape from the fuel tank and facilitate filling fuel into the fuel tank. Of course, other venting schemes and control methods may be used if desired.The forms of the invention disclosed herein are presently preferred embodiments, and many other forms and embodiments are possible. It is not intended to mention here all possible equivalent forms or branches of the invention. It is to be understood that the terms used herein are merely descriptive and not restrictive, and that various changes may be made without departing from the spirit or scope of the invention.

Claims

A charge forming apparatus (10) for an internal combustion engine (12) comprising: a housing having an inlet chamber (100) in which a supply of fuel is received, a venting passage (102) communicating with the inlet chamber (100), and a throttle bore (20) having an inlet through which air is received; a throttle valve (52) carried by the housing and having a valve head (54) movable relative to the throttle bore (20) for controlling fluid flow through the throttle bore (20); and a vent valve (130) supported by the housing and having a valve member (132) movable between an open position in which fluid can flow from the inlet chamber (100) through the vent passage (102) and a closed position in which fluid is inhibited or prevented from flowing from the inlet chamber (100) through the vent passage (102), the vent valve (130) being electrically actuated, the vent valve (130) being actuated as a function of a pressure within the inlet chamber.The apparatus (10) of claim 1, wherein the housing comprises a body (18) and a cover (118) coupled to the body (18), wherein the vent passage (102) is at least partially formed in the cover (118), and the vent valve (130) is supported by the cover (118).The apparatus (10) of claim 1, wherein the vent valve (130) is actuated to maintain a pressure in the inlet chamber (100) between 0.34 mmHg and 19 mmHg.The apparatus (10) of claim 1, further comprising an electrically actuated fuel metering valve (28) supported by the housing and having an inlet (66) connected to the inlet chamber (100) for receiving fuel from the inlet chamber (100) and an outlet (70) connected to the throttle bore (20) and through which fuel is supplied into the throttle bore (20).The apparatus (10) of claim 4, wherein actuation of both the fuel metering valve (28) and the bleed valve (130) is controlled by a single controller (162).The apparatus (10) of claim 5, wherein the controller (162) is supported by the housing.The apparatus (10) of claim 1, also comprising an inlet valve supported by the housing and having a valve (108) that controls fuel flow into the inlet chamber (100).The device (10) of claim 7, wherein the inlet valve is connected to a float (112) housed in the inlet chamber (100) to actuate the inlet valve as a function of the fuel level in the inlet chamber (100).The apparatus (10) of claim 1, also comprising a second venting passage that delivers gaseous materials from a second source to the inlet chamber (100), wherein the flow of gaseous materials from the inlet chamber (100) and from the second source is controlled by the venting valve (130).The apparatus (10) of claim 9, wherein the second source is a fuel tank (202).The apparatus (10) of claim 4, wherein the throttle valve (52) is electrically actuated and wherein actuation of both the fuel metering valve (28) and the throttle valve (52) is controlled by a single controller.The apparatus of claim 5, wherein the throttle valve (52) is electrically actuated, and wherein actuation of each of the fuel metering valve (28), the throttle valve (52), and the bleed valve (130) is controlled by a single controller (162).A fuel system (200) comprising: a fuel tank (202) having a fuel outlet and a vent outlet; a throttle body assembly (10) comprising an inlet chamber (100) in communication with the fuel outlet to receive fuel (206) from the tank (202) and with the vent outlet to receive gaseous materials from the tank (202) into the inlet chamber (100); wherein the throttle body assembly (10) also comprises a vent passage (102) from which gases from the inlet chamber (100) can be vented; and a vent valve (130) supported by the throttle body assembly (10) for controlling venting of the inlet chamber (100) and the fuel tank (202), the throttle body (18) having a throttle bore (20) with an inlet through which air is received and also having an electrically actuated fuel metering valve (28) supported by the housing and having an inlet (66) communicating with the inlet chamber (100) for receiving fuel from the inlet chamber (100) and an outlet (70) communicating with the throttle bore (20) and through which fuel (206) is supplied into the throttle bore (20).The system (200) of claim 13, also comprising a float (112) housed in the inlet chamber (100) and an inlet valve connected to the float (112), the inlet valve being actuated by the float (112) as a function of the fuel level in the inlet chamber (100).The system (200) of claim 13, wherein actuation of both the fuel metering valve (28) and the bleed valve (130) is controlled by a single controller (162).The system (200) of claim 13, further comprising a second venting passage that supplies gaseous materials from a second source into the inlet chamber (100), wherein the flow of gaseous materials from the inlet chamber (100) and from the second source is controlled by the venting valve (130).The system (200) of claim 13, wherein the vent valve (130) is actuated as a function of a pressure within the inlet chamber (100).The system (200) of claim 17, wherein the vent valve (130) is actuated to maintain a pressure in the inlet chamber (100) between 0.34 mmHg and 19 mmHg.

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