阅读说明：本技术 用于燃烧发动机的低压燃料喷射系统 (Low pressure fuel injection system for combustion engine ) 是由 B·J·罗奇 J·C·霍佩 D·F·拉班 于 2020-05-01 设计创作，主要内容包括：在至少一些实施方式中,充量形成装置包括多个节流穿孔、在其中接收燃料的入口室、使入口室与节流穿孔连通的至少一个燃料通道,以及具有与入口室连通的入口、出口以及阀头的阀,该阀头是可移动的并且当入口室中的压力大于阈值压力时容许从入口室穿过出口的流动。(In at least some embodiments, the charge forming device includes a plurality of throttle perforations, an inlet chamber receiving fuel therein, at least one fuel passage communicating the inlet chamber with the throttle perforations, and a valve having an inlet communicating with the inlet chamber, an outlet, and a valve head that is movable and permits flow from the inlet chamber through the outlet when a pressure in the inlet chamber is greater than a threshold pressure.)

1. A charge formation device comprising:

a plurality of throttling perforations;

an inlet chamber in which fuel is received;

at least one fuel passage communicating the inlet chamber with the throttle bore; and

a valve having an inlet in communication with the inlet chamber, an outlet, and a valve head that is movable and permits flow from the inlet chamber through the outlet when pressure in the inlet chamber is greater than a threshold pressure.

2. The apparatus of claim 1, wherein the valve is normally closed and the valve head prevents flow through the outlet when the pressure in the inlet chamber is less than a threshold pressure.

3. The device of claim 1, wherein the valve is a first valve, and wherein the device further comprises a second valve in communication with the inlet chamber, wherein the second valve is electrically actuated between a first position and a second position.

4. The apparatus of claim 3, wherein the apparatus further comprises at least one of a pressure sensor and a temperature sensor, and wherein the second valve is controlled based on an output from at least one of the temperature sensor and the pressure sensor.

5. The apparatus of claim 3, wherein the outlet of the second valve is in communication with the outlet of the first valve.

6. The apparatus of claim 1, wherein the threshold pressure is 3psi or less.

7. The apparatus of claim 1, wherein the valve is adjustable to adjust a threshold pressure at which the valve head will move to permit flow through the valve.

8. The apparatus of claim 7, wherein the valve includes a valve seat defining an inlet of the valve, and the valve head is urged against the valve seat by a biasing member, and the valve includes a spring retainer movable toward or away from the valve seat to vary the force provided by the biasing member on the valve head.

9. The apparatus of claim 1, wherein the valve is electrically actuated to cause the valve head to move relative to a valve seat.

10. The apparatus of claim 9, wherein the apparatus further comprises at least one of a pressure sensor and a temperature sensor, and wherein the valve is controlled as a function of an output from the at least one of the temperature sensor and the pressure sensor.

11. The apparatus of claim 9, wherein the valve is actuated as a function of one or any combination of temperature, pressure, engine speed, and throttle position.

12. The apparatus of claim 10, wherein the pressure sensor and temperature sensor are located within a chamber defined in part by a diaphragm, the diaphragm further defining a reference chamber, wherein the reference chamber is in communication with the inlet chamber such that the diaphragm is acted upon by a pressure corresponding to a pressure within the inlet chamber.

13. The apparatus of claim 10, wherein a temperature sensor is provided and no pressure sensor is provided, and wherein the valve operates according to an output of the temperature sensor.

14. The apparatus of claim 4 or 9, wherein the apparatus further comprises a throttle valve movable relative to at least one throttle perforation to vary the flow rate of fluid through the at least one throttle perforation, and wherein the position of the throttle valve is controlled at least in part as a function of the output of one or both of the temperature sensor and pressure sensor.

15. The apparatus of claim 4 or 9, wherein the apparatus further comprises a controller in communication with the temperature sensor and/or pressure sensor, and wherein the timing of an ignition event in the engine is controlled by the controller at least partially as a function of an output from one or both of the temperature sensor and pressure sensor.

16. The apparatus of claim 9, wherein the apparatus includes a fuel metering valve from which fuel is provided to at least one of the throttling perforations when the fuel metering valve is open, and wherein the valve operates in accordance with whether the fuel metering valve is open or closed.

17. The apparatus of claim 4, wherein the apparatus includes a fuel metering valve from which fuel is provided to at least one of the throttling perforations when the fuel metering valve is open, and wherein the second valve operates in accordance with whether the fuel metering valve is open or closed.

18. The apparatus of claim 1, wherein the throttle bore is formed in a throttle body, and wherein the throttle body includes a cavity spaced from the throttle bore, and wherein a temperature sensor is located within the cavity such that the temperature sensor is responsive to a temperature of the throttle body.

19. The apparatus of claim 18, wherein the temperature sensor is a negative temperature coefficient sensor.

20. A charge formation device comprising:

throttling and perforating;

an inlet chamber in which fuel is received;

at least one fuel passage communicating the inlet chamber with the throttle bore; and

a valve having an inlet in communication with the inlet chamber, an outlet, and a valve head that is movable and permits flow from the inlet chamber through the outlet when pressure in the inlet chamber is greater than a threshold pressure.

21. The apparatus of claim 20, wherein the threshold pressure is 3psi or less.

22. The apparatus of claim 20, wherein the valve includes a valve seat defining an inlet of the valve, and the valve head is urged against the valve seat by a biasing member, and the valve includes a spring retainer movable toward or away from the valve seat to vary the force provided by the biasing member on the valve head.

23. The apparatus of claim 20, wherein the valve is electrically actuated to cause the valve head to move relative to a valve seat.

24. The apparatus of claim 23, wherein the apparatus further comprises at least one of a pressure sensor and a temperature sensor, and wherein the valve is controlled as a function of an output from the at least one of the temperature sensor and the pressure sensor.

25. The apparatus of claim 23, wherein the valve is actuated as a function of one or any combination of temperature, pressure, engine speed, and throttle position.

26. The apparatus of claim 24, wherein the pressure sensor and temperature sensor are located within a chamber defined in part by a diaphragm, the diaphragm further defining a reference chamber, wherein the reference chamber is in communication with the inlet chamber such that the diaphragm is acted upon by a pressure corresponding to a pressure within the inlet chamber.

27. The apparatus of claim 24, wherein a temperature sensor is provided and no pressure sensor is provided, and wherein the valve operates according to an output of the temperature sensor.

28. The device of claim 20, wherein the valve is a first valve, and wherein the device further comprises a second valve in communication with the inlet chamber, wherein the second valve is electrically actuated between a first position and a second position.

Technical Field

The present disclosure relates generally to low pressure fuel injection systems.

Background

Fuel systems that include electronic fuel injectors typically provide fuel to and from the fuel injectors at relatively high pressures. The injection pressure may be constant so that the duration of time the injector is open determines the amount of fuel discharged from the injector. Such systems may be relatively complex and require multiple sensors, some of which may be relatively expensive, such as oxygen sensors in the exhaust gas, as well as a high pressure pump to provide fuel at high pressure to the injector. Such fuel systems are too expensive and complex for a wide range of engine applications.

Disclosure of Invention

In at least some embodiments, a charge forming device includes a plurality of throttle perforations (bores), an inlet chamber in which fuel is received, at least one fuel passage communicating the inlet chamber with the throttle perforations, and a valve having an inlet in communication with the inlet chamber, an outlet, and a valve head that is movable and permits flow from the inlet chamber through the outlet when pressure in the inlet chamber is greater than a threshold pressure.

In at least some embodiments, the valve is normally closed and the valve head prevents flow through the outlet when the pressure in the inlet chamber is less than a threshold pressure. The valve may be a first valve and the device may further include a second valve in communication with the inlet chamber, and the second valve may be electrically actuatable between a first position and a second position. The device may include at least one of a pressure sensor and a temperature sensor, and the second valve may be controlled based on an output from the at least one of the temperature sensor and the pressure sensor. In at least some embodiments, the outlet of the second valve is in communication with the outlet of the first valve.

In at least some embodiments, the threshold pressure is 3psi or less. In at least some embodiments, the valve is adjustable to adjust a threshold pressure at which the valve head will move to permit flow through the valve. The valve may comprise a valve seat defining an inlet of the valve and the valve head may be urged against the valve seat by a biasing member, and the valve may comprise a spring retainer movable towards or away from the valve seat to vary the force provided by the biasing member on the valve head.

In at least some embodiments, the valve is electrically actuated to cause the valve head to move relative to the valve seat. The device may comprise at least one of a pressure sensor and a temperature sensor, and wherein the valve is controlled in dependence on an output from the at least one of the temperature sensor and the pressure sensor. In at least some embodiments, the valve is actuated as a function of one or any combination of temperature, pressure, engine speed, and throttle position. In at least some embodiments, the pressure sensor and the temperature sensor are located within a chamber defined in part by a diaphragm that also defines a reference chamber, and the reference chamber is in communication with the inlet chamber such that the diaphragm is acted upon by a pressure corresponding to a pressure within the inlet chamber. In at least some embodiments, a temperature sensor is provided and a pressure sensor is not provided, and wherein the valve operates according to an output of the temperature sensor.

In at least some embodiments, the apparatus further comprises a throttle valve movable relative to the at least one throttle perforation to vary a flow rate of the fluid through the at least one throttle perforation, and a position of the throttle valve is controlled based at least in part on an output from one or both of the temperature sensor and the pressure sensor. In at least some embodiments, the apparatus further comprises a controller in communication with the temperature sensor and/or the pressure sensor, and the timing of the ignition event in the engine is controlled by the controller based at least in part on an output from one or both of the temperature sensor and the pressure sensor.

In at least some embodiments, the apparatus includes a fuel metering valve from which fuel is provided to at least one of the throttling perforations when the fuel metering valve is open, and the valve is operated depending on whether the fuel metering valve is open or closed.

In at least some embodiments, the throttle bore is formed in the throttle body, and the throttle body includes a cavity spaced from the throttle bore, and wherein the temperature sensor is located within the cavity such that the temperature sensor is responsive to a temperature of the throttle body. The temperature sensor may be a negative temperature coefficient sensor.

In at least some embodiments, the charge forming device includes a throttle bore, an inlet chamber receiving fuel therein, at least one fuel passage communicating the inlet chamber with the throttle bore, and a valve having an inlet communicating with the inlet chamber, an outlet, and a valve head that is movable and permits flow from the inlet chamber through the outlet when a pressure in the inlet chamber is greater than a threshold pressure. In at least some embodiments, the valve is a first valve and wherein the device further comprises a second valve in communication with the inlet chamber, wherein the second valve is electrically actuated between a first position and a second position.

In at least some embodiments, the threshold pressure is 3psi or less. In at least some embodiments, the valve includes a valve seat defining an inlet of the valve, and the valve head is urged against the valve seat by a biasing member, and the valve includes a spring retainer movable toward or away from the valve seat to vary the force provided by the biasing member on the valve head.

In at least some embodiments, the valve is electrically actuated to cause the valve head to move relative to the valve seat. In at least some embodiments, the device further comprises at least one of a pressure sensor and a temperature sensor, and the valve is controlled in accordance with an output from the at least one of the temperature sensor and the pressure sensor. The valve may be actuated based on one or any combination of temperature, pressure, engine speed, and throttle position. The pressure sensor and the temperature sensor may be located within a chamber defined in part by a diaphragm that also defines a reference chamber, and the reference chamber may be in communication with the inlet chamber such that the diaphragm is acted upon by a pressure corresponding to a pressure within the inlet chamber. A temperature sensor may be provided without a pressure sensor, and the valve may be operated according to an output of the temperature sensor.

Drawings

A detailed description of certain embodiments and best mode will be set forth below with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a throttle body assembly having a plurality of perforations through which a fuel and air mixture may be delivered to an engine, the body of the throttle body assembly being shown as transparent to show certain internal components and features;

FIG. 2 is another perspective view of the throttle body assembly;

FIG. 3 is another perspective view of the throttle body assembly with the steam separator cover removed;

FIG. 4 is a perspective cross-sectional view of the throttle body assembly;

FIG. 5 is a perspective cross-sectional view of the throttle body assembly;

FIG. 6 is an enlarged partial perspective view of a portion of the throttle body assembly showing the air introduction path and valve;

FIG. 7 is a partial cross-sectional view of a throttle body assembly including an actuator driven throttle valve and a position sensing arrangement;

FIG. 8 is a perspective view of the coupling;

FIG. 9 is another perspective view of the coupling;

FIG. 10 is a partial cross-sectional view of a throttle body assembly having two throttle bores;

FIG. 11 is a graph (graph) showing waveforms associated with a firing event, pressure near an injector carried by the throttle body, and an injector event;

FIG. 12 is a perspective view of a charge forming device;

FIG. 13 is a perspective view of a vapor separator cover and inlet valve of the device of FIG. 12;

FIG. 14 is a cross-sectional view of the cover and inlet valve showing a solenoid vent valve (vent valve) carried by the cover;

FIG. 15 is a cross-sectional view showing the cap of the pressure relief valve;

FIG. 16 is a diagrammatic view of a charge forming device including one or both of a temperature sensor and a pressure sensor; and

fig. 17 is a diagrammatic view of a portion of a charge forming device including a throttle body having two throttle bores, a control module, and a temperature sensor coupled to the control module.

Detailed Description

Referring in more detail to the drawings, fig. 1-3 illustrate a charge forming device 10 that provides a combustible fuel and air mixture to an internal combustion engine 12 (shown schematically in fig. 1) to support operation of the engine. The charge forming device 10 may be used on a two-stroke or four-stroke internal combustion engine, and in at least some embodiments 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 with more than one throttle bore 20 (shown as two separate bores extending parallel to one another through the body) each having an inlet 22 (fig. 2) through which air is received into the throttle bore 20 and an outlet 24 (fig. 1) connected or otherwise in communication with an engine (e.g., an inlet manifold 26 thereof). If desired, the inlet may receive air from an air filter (not shown), and this air may be mixed with fuel provided from a separate fuel metering valve 28, 29 carried by or in communication with the throttle body 18. During sequential timing periods of the piston cycle, the inlet manifold 26 is typically in communication with the combustion chamber or piston cylinder of the engine. For four-stroke engine applications, as illustrated, the fluid may flow through the inlet valve and directly into the piston cylinder. Alternatively, for two-stroke engine applications, it is typical for air to flow through the crankcase (not shown) before entering the combustion chamber portion of the piston cylinder through a port in the cylinder wall that is intermittently opened by the reciprocating engine piston.

The throttle bore 20 may have any desired shape, including (but not limited to) a constant diameter cylinder or a venturi shape, with the inlet leading to a tapered converging portion that leads to a reduced diameter throat that in turn leads to a tapered diverging portion that leads to an outlet 24. The converging portion may increase the velocity of the air flowing into the throat and create or increase a pressure drop in the region of the throat. In at least some embodiments, a secondary venturi, sometimes referred to as a booster venturi 36, may be located within one or more of the throttle perforations 20 regardless of whether the throttle perforations 20 have a venturi shape. The booster venturis may be identical if desired, and only one will be described further. The booster venturi 36 may have any desired shape and, as shown in fig. 1 and 4, has a converging inlet portion leading to a reduced diameter intermediate throat leading to a diverging outlet. The booster venturi 36 may be coupled to the throttle body 18 within the throttle bore 20, and in some embodiments, the throttle body may be cast from a suitable metal and the booster venturi 36 may be formed as part of the throttle body, in other words, as a feature of the throttle body cast from the same piece of material as the rest of the throttle body is formed. The booster venturi 36 may also be an insert (insert) coupled to the throttle body 18 in any suitable manner after the throttle body is formed. In the example shown, the booster venturi 36 includes a wall 44 defining an internal passage 46 that opens at both its inlet and outlet to the throttle bore 20. A portion of the air flowing through the throttle body 18 flows into and through a booster venturi 36, which increases the velocity of the air and reduces its pressure. The booster venturi 36 may have a central axis 48 (fig. 4) that may be generally parallel to and radially offset from a central axis 50 (fig. 4) of the throttle bore 20, or the booster venturi 36 may be oriented in any other suitable manner.

Referring to FIG. 1, the flow rate of air through the throttle bore 20 and into the engine is controlled at least in part by one or more throttle valves 52. In at least some embodiments, the throttle 52 includes a plurality of heads 54, one received in each bore 20, each of which may include a flat plate coupled to a rotary throttle shaft 56. The shaft 56 extends through a shaft bore 58 formed in the throttle body 18 that intersects the throttle bore 20 and may be generally perpendicular thereto. The throttle valve 52 may be driven or moved by the actuator 60 between an idle position in which the head 54 substantially blocks the flow of air through the throttle bore 20 and a fully open or wide open position in which the head 54 provides minimal restriction to the flow of air through the throttle bore 20. In one example, the actuator 60 may be an electric drive motor 62 coupled to the throttle shaft 56 to rotate the shaft and thus the valve head 54 within the throttle bore 20. In another example, the actuator 60 may include a mechanical linkage (linkage), such as a lever attached to the throttle shaft 56 to which a Bowden wire may be connected to manually rotate the shaft 56 as needed and as is known in the art. In this manner, multiple valve heads may be carried on a single shaft and rotated in unison within different throttling perforations. A single actuator may drive the throttle valve shaft and a single throttle position sensor may be used to determine the rotational position of the throttle valve (e.g., the valve head 54 within the throttle bore 20).

The fuel metering valve 28 may be identical for each perforation 20, and thus only one is further described. The fuel metering valve 28 may have an inlet 66 to which fuel is delivered, a valve element 68 (e.g., a valve head) that controls the flow rate of the fuel, and an outlet 70 located downstream of the valve element 68. To control actuation and movement of valve member 68, fuel metering valve 28 may include or be associated with an electrically driven actuator 72, such as, but not limited to, a solenoid. Among other things, the solenoid 72 may include a housing 74 received within a cavity 76 in the throttle body 18, a coil 78 wound about a spool 80 received within the housing 74, an electrical connector 82 arranged to couple to a power source to selectively energize the coil 78, and an armature 84 slidably received within the spool 80 for reciprocating movement between an advanced position and a retracted position. The valve element 68 may be carried by the armature 84 or otherwise movable relative to a valve seat 86, which may be defined within one or both of the solenoid 72 and the throttle body 18. When the armature 84 is in its retracted position, the valve element 68 is removed from or 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 element 68 may close against or bear against the valve seat 86 to inhibit or prevent fuel flow through the valve seat. In the example shown, the valve seat 86 is defined within the cavity 76 of the throttle body 18 and may be defined by features of the throttle body or by a member inserted into and carried by the throttle body or solenoid case 74. Solenoid 72 may be constructed as set forth in U.S. patent application serial No. 14/896,764. The inlet 66 may be centered or generally coaxially positioned 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 may alternatively be used, including but not limited to different solenoid valves or commercially available fuel injectors, if desired in a particular application.

Fuel flowing through the valve seat 86 (e.g., when the valve element 68 is moved from the valve seat by retraction of the armature 84) flows to the metering valve outlet 70 for delivery into the throttling perforations 20. In at least some embodiments, when the booster venturi 36 is included in the throttle bore 20, fuel flowing through the outlet 70 is directed into the booster venturi 36. In embodiments in which the booster venturi 36 is spaced from the outlet 70, an outlet tube 92 (fig. 4)) may extend from a passage or port defining at least a portion of the outlet 70 and through an opening in the booster venturi wall 44 to communicate with the booster venturi passage 46. The tube 92 may extend into and communicate with the throat 40 of the booster venturi 36, wherein the negative or sub-atmospheric pressure signal may have a maximum magnitude, and the velocity of the air flowing through the booster venturi 36 may be maximum. Of course, the tube 92 may open into different regions of the booster venturi 36 as desired. In addition, the tube 92 may extend through the wall 44 such that the end of the tube protrudes into the booster venturi passage 46, or the tube may extend through the booster venturi passage such that the end of the tube intersects the opposite wall of the booster venturi, and may include holes, slots, or other features through which fuel may flow into the booster venturi passage 46, or the end of the tube may be within the opening 94 and recessed from or spaced apart from the passage (i.e., not protruding into the passage).

In addition, as shown in fig. 4 and 6, when more than one metering valve is used, the air introduction passages 172, 173 may be used in conjunction with each or any of the plurality of metering valves 28. The air introduction passages 172, 173 may extend from a portion of the throttle penetration 20 upstream of the fuel outlet of its associated metering valve, and may communicate with a fuel passage leading to the fuel outlet of the metering valve. In the example shown, the air introduction passages 172, 173 are introduced from the inlet end 22 of the throttle body 18 and open into the fuel outlet passage.

In examples where the fuel tube 92 extends into the booster venturi 36, the inlet passages 172, 173 may extend into or communicate with the fuel tube (as shown in fig. 6) to provide air from the inlet passages and fuel from the metering valve 28 into the fuel tube 92 where it may mix with air flowing through the throttle perforations 20 and the booster venturi 36.

Jets of other flow controllers may be provided in the lead-in channels 172, 173 to control the flow rate of air in the channels, if desired. In addition to or in lieu of a jet or other flow controller, the flow rate through the introduction passages 172, 173 may be at least partially controlled by a valve. The valves may be located anywhere along the channels 172, 173, including upstream of the channel inlets. In at least one embodiment, the valve may be at least partially defined by a throttle shaft 56. In such an example, the introduction passage 172 intersects or communicates with the throttle shaft bore such that air flowing through the introduction passage flows through the throttle shaft bore before the air is discharged into the throttle bore. A separate void, such as a hole 174 or notch, may be formed in the throttle shaft 56 (e.g., through the shaft, or into a portion of the shaft's circumference) and aligned with the passages 172, 173, as shown in fig. 6. As throttle shaft 56 rotates, the degree to which the gap aligns or aligns with the lead-in passage changes. Thus, the effective or open flow area through the valve changes, which may change the flow rate of air provided from the introduction channel. If desired, in at least one position of the throttle valve, the interspace may not be open at all towards the introduction channel, so that an air flow from the introduction channel through the throttle valve perforations does not occur or is substantially prevented. Thus, the flow of air provided from the introduction passage to the throttle bore may be controlled at least partially according to the throttle position.

Fuel may be provided to metering valve inlet 66 from a fuel source, and when valve element 68 is not closed on valve seat 86, fuel may flow through valve seat and metering valve outlet 70 and to throttle perforations 20 to mix with air flowing therethrough and deliver to the engine as a fuel and air mixture. The fuel source may provide fuel to the metering valve 28 at a desired pressure. In at least some embodiments, the pressure can be ambient or slightly superatmospheric up to about, for example, 6psi above ambient pressure.

To provide fuel to metering valve inlet 66, throttle body assembly 10 may include an inlet chamber 100 (fig. 3) into which fuel is received from a fuel supply, such as a fuel tank. The throttle body assembly 10 may include a fuel inlet 104 that opens into the inlet chamber 100. In systems where the fuel pressure is substantially at atmospheric pressure, the fuel stream may be gravity fed to the inlet chamber 100. In at least some embodiments, as shown in fig. 3 and 4, the valve assembly 106 can control the flow of fuel into the inlet chamber 100. Valve assembly 106 may include a valve element 108 and may include or be associated with a valve seat such that a portion of valve element 108 may be selectively engaged with the valve seat to inhibit or prevent fluid flow through the valve seat, as will be described in greater detail below. The valve element 108 may be coupled to an actuator 112 that moves the valve 108 relative to a valve seat, as will be explained in more detail below. The bleed port or passage 102 may communicate with the inlet chamber and with the engine inlet manifold or other location as desired, as long as the desired pressure within the inlet chamber 100 is achieved in use, which may include atmospheric pressure. The fuel level in the inlet chamber 100 provides a head or pressure of 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 by an actuator 112, which in the example shown includes or is defined by a float (float) that is received in the inlet chamber and is responsive to the fuel level in the inlet chamber. The float 112 may float in the fuel and provide a lever pivotally coupled to the throttle body 18 or a cap 118 coupled to the body 18 by a pin, and the valve 108 may be connected to the float 112 so as to move as the float moves in response to changes in the fuel level within the inlet chamber 100. When there is a desired maximum fuel level in the inlet chamber 100, the float 112 has moved to a position in the inlet chamber in which the valve 108 engages and closes against the valve seat, which closes the fuel inlet 104 and prevents further flow of fuel into the inlet chamber 100. When fuel is discharged from the inlet chamber 100 (e.g., through the metering valve 28 to the throttle bore 20), 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 so that the fuel inlet 104 opens again. 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, such as by a recess formed in the throttle body, and a cavity in a cover 118 carried by the throttle body and defining a portion of the housing of the throttle body assembly 10. The outlet 120 (fig. 5) of the inlet chamber 100 opens into the metering valve inlet 66 of each metering valve 28, 29. In order for the fuel to be always available at the metering valve 28 when the fuel is within the inlet chamber 100, in at least some embodiments, the outlet 120 may be an open passage without any intervening valve. The outlet 120 may extend from a bottom or lower portion of the inlet chamber so that fuel may flow to the metering valve 28 at atmospheric pressure.

In use of the throttle body assembly 10, fuel is retained in the inlet chamber 100, and hence the outlet 120 and the metering valve inlet 66, as described above. When the metering valve 28 is closed, no or substantially no fuel flows through the valve seat 86, and thus no fuel flows to the metering valve outlet 70 or to the throttling perforations 20. To provide fuel to the engine, the metering valve 28 is opened and fuel flows into the throttle bore 20, mixes with air and is delivered to the engine as a fuel and air mixture. The timing and duration of the metering valve opening and closing can be controlled by a suitable microprocessor or other controller. Timing of fuel flow (e.g., injection), or when the metering valve 28 is open during an engine cycle, can cause the pressure signal at the outlet 70 to vary, and thus vary the pressure differential across the metering valve 28 and the resulting fuel flow rate into the throttle bore 20. In addition, both the magnitude of the engine pressure signal and the air flow rate through throttle valve 52 vary significantly between when the engine is operating at idle and when the engine is operating wide open. Jointly, for any given fuel flow rate, the duration that the metering valve 28 is open will affect the amount of fuel flowing into the throttle bore 20.

The inlet chamber 100 may also be used to separate liquid fuel from gaseous fuel vapor and air (e.g., as a liquid/vapor separator). The liquid fuel will settle into the bottom of the inlet chamber 100 and the fuel vapor and air will rise to the top of the inlet chamber where it can flow out of the inlet chamber (and thus into the inlet manifold and then to the engine combustion chamber) through the bleed passage 102 or bleed outlet. To control the venting of gas from the inlet chamber 100, a vent valve 130 may be provided at the vent passage 102. The bleed valve 130 may include a valve element 132 that moves relative to a valve seat to selectively allow fluid flow through an orifice (vent) or bleed passage 102. To allow further control of flow through the bleed passage 102, the bleed 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 fig. 3, to control actuation and movement of the valve element 132, the bleed valve 130 may include or be associated with an electrically driven actuator such as, but not limited to, a solenoid 136. Among other things, the solenoid 136 may include a housing received within a cavity in the throttle body 18 or cover 118 and retained therein by a retaining plate or body, a coil wound around a bobbin received within the housing, an electrical connector 146 arranged to couple to a power source to selectively energize the coil, an armature slidably received within the bobbin for reciprocating movement between an advanced position and a retracted position, and an armature stop. The valve element 132 may be carried by the armature or otherwise moved by the armature relative to a valve seat, which may be defined within one or more of the solenoid 136, the throttle body 18, and the cover 118. When the armature is in its retracted position, the valve element 132 is removed from or spaced from the valve seat and fuel can flow through the valve seat. When the armature 148 is in its extended position, the valve element 132 may close against or bear against the valve seat 134 to inhibit or prevent fuel flow through the valve seat. The solenoid 136 may be constructed as set forth in U.S. patent application serial No. 14/896,764. Of course, other valves may alternatively be used, including but not limited to different solenoid valves (including but not limited to piezoelectric-type solenoid valves) or other electrically actuated valves, if desired in a particular application.

The vent passage 102 or vent outlet may be coupled to a filter or vapor canister that includes an adsorbent material, such as activated carbon, to reduce or remove hydrocarbons from the vapor. The bleed passage 102 may additionally or alternatively be coupled to an inlet manifold of the engine, where vapors may be added to the combustible fuel and air mixture provided from the throttle bore 20. In this manner, vapor and air flowing through the relief valve 130 are directed to downstream components as needed. In the illustrated embodiment, the outlet passage 154 extends from the cover 118 downstream of the valve seat 134 and to the inlet manifold of the engine (e.g., via the throttle bore 20). While the outlet passage 154 is shown as being at least partially defined in a conduit that extends (routed) outside of the cap 118 and throttle body 18, the outlet passage 154 may alternatively be at least partially defined by one or more perforations or voids formed in the throttle body and/or cap, and or by a combination of an internal void/passage and external conduit(s).

In at least some embodiments, the cap 118 defines a portion of the inlet chamber 100 and the bleed passage 102 extends at least partially within the cap and communicates with the inlet chamber 100 at a first end and with an outlet from a throttle body (e.g., cap) at a second end. A bleed valve 130 and a valve seat 132 are disposed between the first and second ends of the bleed passage 102 such that the bleed valve controls flow through the bleed passage. In the illustrated embodiment, the vent passage 102 is entirely within the cap 118, and the vent valve 130 is carried by the cap, e.g., within a cavity formed in the cap.

In at least some embodiments, the pressure in the bleed 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, when the bleed passage 102 is in communication with the inlet manifold or with the air cleaner cartridge/filter, a sub-atmospheric pressure may exist within the bleed passage. The sub-atmospheric pressure, if 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. Thus, closing the bleed valve 130 may inhibit or prevent communication of the sub-atmospheric pressure from the bleed passage 102 with the inlet chamber 100. A pressure sensor responsive to the pressure in the bleed passage 102 or, for example, in the inlet manifold, may provide a signal for controlling, at least in part, the actuation of the bleed valve 130 to improve control of the pressure in the inlet chamber as a function of the sensed pressure. Additionally or alternatively, the bleed valve 130 may close to allow some positive superatmospheric pressure to exist within the inlet chamber 100, which may improve fuel flow from the inlet chamber to the throttle bore 20. And the bleed valve 130 may open to allow an engine pressure pulse (e.g., from the inlet manifold) to increase the pressure within the inlet chamber 100. As mentioned above, the opening of the relief valve 130 may be timed with such pressure pulses by a pressure sensor or otherwise. These examples allow for better control of the fuel flow from the inlet chamber 100 and, therefore, better control of the fuel and air mixture delivered from the throttling perforations 20. In this manner, the bleed valve 130 may be opened and closed as needed to bleed gas from the inlet chamber 100 and control the pressure within the inlet chamber.

Still further, it may be desirable to close the bleed passage 102 to avoid fuel in the inlet chamber 100 from deteriorating over time (due to evaporation, oxidation, etc.), such as during storage of the device with which the throttle body assembly 10 is used. In this manner, the bleed valve 130 may be closed when the device is not in use to reduce the likelihood or rate at which fuel in the throttle body assembly 10 deteriorates.

Finally, as the bleed valve moves from an opening stroke to closing, the movement of the armature and valve element 132 displaces air/vapor in the bleed passage 102 toward and into the inlet chamber 100, which may increase the pressure in the inlet chamber. Repeated actuation of the relief valve 130 may then provide a pressure increase, even if relatively small, that facilitates fuel flow from the inlet chamber 100 to the throttle bore 20.

In at least some embodiments, the pressure within the inlet chamber 100 may be controlled between 0.34mmHg and 19mmHg by actuation of the bleed valve 130. In at least some embodiments, the bleed valve 130 may be repeatedly opened and closed at a cycle time between 1.5ms and 22 ms. And in at least some embodiments, the bleed valve 130 may be controlled at least when the throttle valve is at least 50% of its way between idle and wide open positions (e.g., between 50% and 100% of angular rotation from idle to wide open), for example, because the inlet manifold pressure may be greater in this range of throttle positions and thus more likely to interfere with the pressure in the inlet chamber.

The bleed valve 130 may be actuated by a controller 162 (fig. 1, 4, and 5) that controls when electrical power is supplied to the solenoid 136. Controller 162 may be the same controller that actuates fuel metering valve 28 or a separate controller. Additionally, a controller 162 that actuates one or both of the bleed valve 130 and the fuel metering valve 28 may be mounted on or otherwise carried 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 carried within a sub-housing 164 that is mounted to or otherwise carried by the throttle body 18 and/or the cap 118, and 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 throttling valve (e.g., when rotated by the motor 62, as shown and described above). Additionally, information from one or more sensors may be used to at least partially control operation of the bleed valve, and the sensor(s) may be in communication with a controller that controls actuation of the bleed valve.

The dual bore throttle body and fuel injection assembly may be used to provide a combustible fuel and air mixture to a multi-cylinder engine. The assembly may improve cylinder-to-cylinder air-fuel ratio balancing, engine starting, and overall operating quality and performance as compared to assemblies having a single throttle penetration and a single fuel injector or fuel injection point/location.

The system or assembly may include the low pressure fuel injection system described above with any of the additional options: a single throttle body assembly having a plurality of throttle bores; one or more vapor separators integrated within the throttle body assembly; each throttling perforation having at least one ejector; optionally a booster venturi for the ejector(s); a single engine control module/controller; a single throttle shaft comprising a plurality of throttle heads on the shaft, one throttle head in each throttle bore; a single throttle position sensor; may comprise a single throttle actuator that is electronically controllable; two ignition coils or a double-ended ignition coil may be included.

As shown in fig. 7, a throttle body or other charge forming device may include one or more throttle perforations 20, and a throttle valve 52 associated with each throttle perforation 20. The throttle valve 52 may be separate or a single throttle valve shaft 56 may include multiple valve heads 54 that rotate with the shaft 56 between a first or idle position and a second or open position, which may be a wide open or fully open position. In the example shown in fig. 4, the throttle valve shaft 56 has two valve heads 54 mounted thereon, which are shown as thin discs in a double butterfly valve arrangement. In the first position, the valve head 54 is generally perpendicular to the fluid flow through the throttle bore 20 and provides a maximum restriction to the fluid flow through the throttle bore 20 (wherein generally perpendicular includes vertical and an orientation within 15 degrees of vertical). In the second position, the valve head 54 is generally parallel to the fluid flow through the throttle bore 20 and may provide minimal restriction to the fluid flow through the throttle bore 20 (where generally parallel includes parallel and an orientation within 15 degrees of parallel).

As mentioned above, the throttle valve 52 may be driven or moved by an actuator 60, which may be an electric drive motor 62 coupled to the throttle shaft 56 to rotate the shaft and, thus, the valve head 54 within the throttle bore 20. As shown in FIG. 4, a coupling 180 may drivingly connect the actuator 60 to the throttle shaft 56. The coupling 180 may include a first recess 182 that receives an end 184 of the throttle valve shaft 56 therein and a second recess 185 that receives a drive shaft 186 of the actuator 60 therein. Suitable anti-rotation features (e.g., complementary non-circular portions or surfaces) are provided between the coupler 180 and the shafts 56 and 186 to facilitate rotation of the throttle shaft 56 when the drive shaft 186 is rotated. If desired, the coupling may be flexible, that is, it may twist or flex slightly to reduce impact forces from rapid movement (e.g., greater acceleration or deceleration) of the assembly. And the coupling 180 may be resilient such that it does not twist or flex in order to achieve the commanded amount of rotation of the throttle valve 52 (that is, the rotation of the actuator 60 is accurately transferred to the throttle valve 52 and results in the same amount of rotation of the throttle valve) when the force causing the twist is removed or sufficiently reduced.

In FIG. 4, the coupling 180 is disposed on an end 184 of the valve shaft 56 opposite an end 188 of the valve shaft 56 adjacent the circuit board 166. The end 188 of the valve shaft 56 includes or is coupled to a second coupling 190 that carries a sensor element 192 that rotates with the valve shaft 56. A sensor 194 responsive to movement of the sensor element 192 may be mounted to the circuit board 166 or elsewhere as desired. In at least some embodiments, the sensor element 192 is a magnet and the sensor 194 responds to movement of the magnetic field of the magnet 192 as the valve shaft 56 rotates. This provides a non-contact sensor arrangement which is capable of accurately determining the rotational or angular position of the throttle valve.

In FIG. 7, a coupling 200 interconnects the actuator 60 with the valve shaft 56 and also carries or otherwise includes a sensor element 192. Such a coupling 200 is mounted on the end 188 of the valve shaft 56 adjacent the circuit board 166 and/or the sensor 194. As shown in fig. 7-9, the coupling 200 has a first drive feature 202 that engages the drive shaft 186 of the actuator 60 such that the coupling 200 rotates in unison with the drive shaft 186, and a second drive feature 204 that engages the valve shaft 56 such that the valve shaft 56 and the coupling 200 rotate in unison. The drive features 202, 204 may comprise recesses or sockets into which portions of the shafts 56, 186 extend, have non-circular portions or surfaces that prevent rotation of the coupler 200 relative to each shaft 56, 186, or the coupler may comprise protrusions that are received in sockets or cavities of the shafts 56, 186, or some combination of such features. In the example shown, the first drive feature 202 includes two oppositely facing flat surfaces 205 (fig. 9) and the drive shaft end 188 is complementarily shaped, and the second drive feature 204 includes one flat surface 206 (fig. 8) that is generally D-shaped and the drive shaft 186 is complementarily shaped. Of course, other non-circular shapes and arrangements may be used as desired. The drive features 202, 204 may also be rounded if desired, and adhesive, set screws, or other connections may also be provided between the shafts 56, 186 and the coupling 200 to provide the desired co-rotation, if desired. As described above, the coupling 200 may be formed of at least somewhat flexible material to, for example, dampen impact forces and vibrations, and yet be resilient so that a desired or commanded rotation of the valve shaft 56 ultimately occurs.

The coupling 200 may include a cavity 207 that receives the magnet 192 therein, and the magnet 192 and the cavity 207 may have complementary anti-rotation features 209, 211 that inhibit or prevent the magnet 192 from rotating relative to the coupling 200. The anti-rotation features 209, 211 may include engaged planar surfaces or other complementary non-circular geometric features, and/or an adhesive or other connector may be used between the magnet 192 and the coupling 200. Thus, the rotational position of the magnet 192 may more accurately represent the rotational position of the coupling 200 and the valve shaft 56. To facilitate proper assembly and/or calibration of the sensor assembly, or for other reasons, a flag 213 or some indicia may be provided on the magnet 192 to indicate the polarity of that portion of the magnet. In the example shown, the magnet 192 may be received in the cavity 207 in two different orientations (e.g., it may be flipped), and the markings may help ensure that the magnet 192 is installed in the desired orientation.

In at least some embodiments, as shown in fig. 7, one of the drive shaft 186 or the valve shaft 56 extends through a void 208 in the circuit board 166. This enables the sensor element 192 to be positioned close to the sensor 194 (e.g., less than 8mm apart) to improve position sensing. In the example shown, the motor 210 of the actuator 60 is on a first side of the circuit board 166 and the coupler 200 is on an opposite second side of the circuit board 166, and the drive shaft 186 extends through a void 208 in the circuit board, and an alignment void/boss 212 in the sub-housing 164 that can support and guide the rotation of the drive shaft 186. The valve shaft 56 may alternatively extend through a void 208 in the circuit board 166, and the coupler 200 and the drive shaft 186 may be located on a first side of the circuit board 166 that is the side opposite the throttle bore 20.

In the throttle body shown in fig. 10, a passage 220 is provided that communicates with the throttle bore 20 at a first end 222. The channel also communicates with a pressure sensor 224, which is shown mounted to the circuit board 166. Thus, in such embodiments, the passage 220 extends through the sub-housing 164 to a second end that is open to the area in which the pressure sensor 224 is positioned. The pressure in the orifice bore 20 in the region of the first end 222 of the passage 220 communicates with a pressure sensor 224 that provides an output signal corresponding to the sensed pressure.

In at least some embodiments, the first end 222 of the passage 220 is disposed near the area where fuel is injected into the throttle bore 20. The throttle bore has an axis 226. In at least some embodiments, an imaginary plane 228 perpendicular to the axis 226 and extending through the center of the injection port 230 through which fuel enters the throttle bore 20 intersects or is within 1 inch of the first end 222 of the passage 220. In the example shown, fuel enters the throttle bore 20 through a port 230 formed in a booster venturi 36 located within the throttle bore 20, as described above with reference to, for example, FIG. 4. Of course, other arrangements may be used. Thus, the output from the pressure sensor 224 is indicative of the pressure in the region of the fuel injection port 230 and thus indicative of the pressure acting on the fuel at the injection port 230. In at least some embodiments, the timing of fuel injection may be coordinated or selected based on such sensed pressure to control the flow of fuel into the throttle bore 20. Further, when controller 162 is powered on, which may occur prior to engine start-up, controller 162 may interrogate or receive a signal from pressure sensor 224 for a barometric pressure reference, which may be used to determine initial ignition timing and/or fuel/air mixture calibration or for other engine control purposes.

In the illustration shown in fig. 11, the first waveform 240 relates to the voltage induced in the coils of the engine ignition system, such as by a magnet mounted to the engine flywheel. The second waveform 242 relates to a fuel metering valve or fuel injector control signal, that is, the waveform shows when voltage is applied to open the fuel injector(s) as described above. And a third waveform 244 shows the pressure sensed by sensor 224. Shown in this illustration is an engine revolution slightly greater than one, as can be seen in the two examples in ignition coil/sensor waveform 240, where the flywheel magnet induces a voltage in the ignition system coil. Within such engine revolutions, when the engine inlet valve opens and the downward traveling piston creates a negative relative pressure in the engine inlet, the pressure at sensor 224 decreases between points 246 and 248. There is typically no negative or positive relative pressure signal when the inlet valve is closed. The time when a negative pressure occurs at the injection location, which may or may not occur within the throttle body (that is, the injector may be located outside the throttle body and pressure may be taken in the region of the injector outlet, as mentioned above), is the optimal time for the low pressure injection system to open the injector and control fuel injection, as a greater fuel flow rate may be achieved with such a negative engine pressure signal that facilitates fuel flow from port 230.

Generally, the greater the magnitude of the negative relative pressure, the more fuel will flow from the injector for a given amount of time that the injector is open and allowed to flow. Thus, the beginning of negative pressure (generally indicated at 246) to the end of negative pressure (generally indicated at 248) may be an optimal time period in which to inject fuel, at least in which the pressure is measured at or very near the injection location. Of course, in at least some instances, fuel may be provided only during a portion of the negative pressure signal, and improved control of fuel injection events may be achieved by timing injection events to a desired portion of the negative pressure signal, which does not necessarily include the maximum relative pressure.

Thus, injection timing may be controlled based on the instantaneous pressure at or near the injection outlet or port. The pressure may be measured or sensed continuously, or sampled at a fixed rate, as desired. Additionally, the injection event may be dependent on one or more pressure thresholds so that a known fuel flow rate may be obtained and the efficiency of the fuel injection event may be improved. In the example shown in fig. 11, a signal, indicated at 250, is provided from a controller to a fuel injector (or what may be considered a fuel metering valve of the fuel injector) to open a valve of the fuel injector and facilitate fuel flow when the pressure signal exceeds a threshold relative pressure. Thus, the injector valve does not close and fuel is not delivered from the injector until the pressure signal exceeds the threshold. The injection strategies described herein may improve fuel injection efficiency in, but are not limited to, situations where the sensed or calculated crankshaft angular position may not be as accurate as desired, such as during engine acceleration or deceleration. Furthermore, any changes in the pressure signal due to degradation of the engine system (pumping efficiency due to wear, air filter clogging, etc.) can be compensated for in order to continue injecting fuel at the optimal relative negative pressure despite changes in the shape, magnitude, or timing of the relative negative pressure pulse (which cannot be compensated instantaneously based on calibration of engine crankshaft angular displacement/position).

Manifold or inlet pressure may vary depending on both engine speed and throttle position(s). In at least some embodiments, the engine and charge formation combination may be tested and the inlet pressure recorded across a range of engine speeds and throttle positions. Such data may be provided to the controller 168, and the controller may then actuate the fuel injectors (or metering valves) based on the data rather than based on signals from the pressure sensor. Advantageously, the cost and complexity of the pressure sensor may be eliminated from the device while maintaining advantages, at least when engine speed (e.g., from a VR sensor) and throttle position are known in use of the engine. Thus, a method of operating a fuel injection or engine may generally include determining an engine speed and a throttle position, and controlling fuel injection based on the determined information. The pressure sensor may also be used in conjunction with the pressure signal data described above, wherein the data provides cross-checking or validation of the pressure signal, for example, to verify proper operation of the pressure sensor and/or the engine over a length of time (e.g., the useful life of the engine).

In some cases, such as when the engine is in a hot ambient and/or exposed to sunlight, the throttle body assembly and engine may become very warm or hot, which may be exacerbated if the engine is running in a warmer ambient or otherwise and thus becomes warm from operation and then shut down. In some cases, the charge forming device may be in proximity to an engine exhaust or other heat source. With any one or more heating sources, in at least some embodiments, the throttle body can reach a temperature of one hundred degrees celsius and the fuel within the inlet chamber 100 can become hot, which can significantly increase the pressure within the inlet chamber 100.

Then, when the hot engine is starting and the metering valve(s) 28, 29 or fuel injector is open to provide fuel to the engine, fuel may flow at a higher volumetric flow rate than desired due to the pressure differential between the inlet chamber 100 and the outlet of the metering valve(s) or fuel injector. For example, the pressure at the fuel injector at these higher temperatures may exceed 15psi, and in some embodiments, up to 20 psi. This results in excessive fuel delivery (which may result in up to 30 or more times the amount of fuel delivered from the injector in at least some embodiments), which may prevent the engine from starting, or otherwise affect engine performance and emissions from the engine. In addition, the higher pressure fuel experiences a significant reduction in pressure as it flows out of the inlet chamber, and particularly as the fuel flows through a smaller area flow path (e.g., a jet or flow restrictor that creates a pressure drop) and/or the outlet of the metering valve(s), which may be of relatively small size and is typically at ambient pressure. Such a pressure drop may result in at least some vaporization in the fuel that results in a smaller desired liquid fuel ratio delivered from the metering valve(s) and inhibits or potentially prevents engine startup.

The charge forming device 260 shown in fig. 12 may include a throttle body having one or more throttle perforations 20 and a vapor separator 262 having a cap 264, which may be similar to the vapor separator defined at least in part by the inlet chamber 100 and cap 118 described above, with at least some of the differences set forth below. The vapor separator 262 can include an inlet chamber 266 having a float (112) controlling the inlet valve 108 (fig. 14) and a relief valve 130 that can be actuated by or include the solenoid 136. These components may function as described above with respect to charge forming device 10.

Further, the vapor separator 262 may include a pressure relief valve 268 having an inlet 270 in communication with the inlet chamber 266 and an outlet 272 in communication with the bleed port or passage 102. The pressure relief valve 268 is arranged to open and vent the inlet chamber 266 to the vent passage 102 when the pressure within the inlet chamber 266 exceeds a threshold. This limits the pressure within the inlet chamber 266 to the threshold pressure even in situations where the fuel within the inlet chamber is hot. Thus, the maximum pressure differential across the metering valve(s) 28, 29 is limited to the difference between the threshold pressure and the pressure at or downstream of the metering valve 28, 29, which is typically atmospheric pressure prior to starting the engine, and which varies during operation of the engine. In at least some embodiments, the threshold pressure is set at a level that prevents evaporation of fuel as it flows through a restriction in the fuel path and/or through the metering valve outlet. In at least some embodiments, the threshold pressure in the inlet chamber 266 is below 3psi, and in at least some embodiments may be below 2psi, and in at least some embodiments between 1psi and 1.5 psi. A certain positive pressure reduces fuel evaporation and preventing the pressure from being too high also limits or reduces fuel evaporation, as mentioned above.

One form of pressure relief valve 268 is shown in fig. 15. The valve 268 includes a valve seat 274 defining an inlet 270 in communication with the inlet chamber 266 and a valve head 276 urged against the valve seat 274 by a biasing member, shown as a coil spring 278. The spring retainer 280 may be adjustably carried by the housing 282 (or directly by the body of the charge forming device, such as the cap 264), and movement of the retainer 280 toward or away from the valve seat 274 changes the force provided by the spring 278 on the valve head 276, which changes the pressure required at the inlet 270 to move the valve head 276 away from the valve seat 274. In this manner, the relief valve 268 defines a threshold or maximum pressure in the inlet chamber 266. The outlet 272 may be at least partially defined by a port in the housing 282 or in the cap 264 or other portion of the charge forming device. Of course, other valve configurations may be used and what is shown and described is only one possibility.

The bleed valve 130 may additionally or alternatively be operated to control the pressure within the vapor separator 262 as a function of one or any combination of temperature, pressure, engine speed, and throttle position. Feedback from the pressure sensor and/or the temperature sensor may be used to determine a control strategy for the bleed valve 130, and in at least some embodiments the bleed valve 130 may be used to control the pressure in the inlet chamber 266 without any relief valve 268.

When the pressure within the inlet chamber 266 is above the threshold pressure, the relief valve 130 may open. The pressure within the inlet chamber 266 may be measured or determined directly, such as by a sensor in communication with the inlet chamber, or the pressure may be inferred, such as based on the temperature of the inlet chamber. In FIG. 16, a pressure and temperature sensor 284 (which may be a combination sensor or a separate sensor) is located within a chamber 286 defined in part by a diaphragm 288 that also defines a reference chamber 290 in communication with the inlet chamber 266 via a passage 292. The sensor 284 may be coupled to the controller 168 by a suitable wire 294 or otherwise as desired. Thus, the temperature and pressure of the inlet chamber 266 may be known and monitored to control the pressure therein by opening and closing the bleed valve 130. If only a temperature sensor is provided, the bleed valve 130 may then be controlled as a function of temperature, with the pressure within the inlet chamber 266 being predetermined (e.g., empirically tested) or calculated or otherwise assumed at various temperatures to provide some data or algorithm for controlling the bleed valve 130 and thus the pressure within the inlet chamber 266. Generally, the higher the temperature, the higher the pressure, and thus the more often the relief valve opens (e.g., opens more frequently and/or opens for a longer duration). But for higher temperatures and pressures there is also a risk of fuel evaporation, so the bleed valve 130 may be controlled to maintain a desired pressure within the inlet chamber 266, at least when the temperature is above a threshold. When the temperature is below the threshold, the risk of evaporation may be low enough that the relief valve 130 does not need to maintain a super-atmospheric pressure.

The temperature and/or pressure information may also be used to control other aspects of engine operation, such as throttle position and/or ignition timing. When attempting to start the engine, knowledge of the inlet chamber 266 temperature or the temperature of at least a portion of the charge forming device can identify the severity of the conditions in which the engine will operate and which are used to allow for auxiliary action to be taken (e.g., adjusting throttle position and/or ignition timing). For example, a more closed throttle may encourage more fuel to flow during start-up, but generally it is desirable to increase airflow and reduce pressure during start-up, so improved start-up is a balance of several factors.

When the metering valve(s) are open, the pressure in the inlet chamber 266 may also vary, and the bleed valve 130 may be controlled according to the position/state of the metering valve(s). For example, the bleed valve 130 may be opened at all times when the engine is operating (and therefore the metering valves are selectively opening) or when each metering valve 28 and 29 is open, or only when either of the valves 28, 29 is open.

As shown in fig. 17, the temperature may also be determined in other manners, such as by a sensor 300 received within a cavity 302 of the throttle body 18 and in communication with a sensor element on the controller 168 or the circuit board 166. In at least some embodiments, the component is a thermistor, which can be a Negative Temperature Coefficient (NTC) sensor having leads 304 attached to the circuit board 166. The cavity 302 may be open to or at least partially defined by the sub-housing 164. In the example shown, the sub-housing 164 has a hollow protrusion 306 received in the cavity 302, and in this protrusion the sensor/NTC lead is arranged for facilitating coupling of the sensor 300 to the circuit board 166 without sealing the opening between the sensor and the circuit board. To improve temperature sensing, the cavity 302 may be filled with a thermal paste.

The forms of the invention herein disclosed constitute presently preferred embodiments and many other forms and embodiments are possible. It is not intended herein to mention all of the possible equivalent forms or ramifications of the invention. It is understood that the words which have been used herein are words of description rather than limitation, and various changes may be made without departing from the spirit or scope of the invention.

As used in this specification and claims, the terms "for example," "for instance," "such as," "for example," "such as," and "like," and the verbs "comprising," "having," "including," and their other verb forms when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.