REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Serial No. 62/420,251 filed on November 10, 2016 the entire contents of which are incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to charge forming device that provides air, fuel or both for use by an engine.

BACKGROUND

A carburetor is used to provide a combustible charge or mixture of fuel and air to an internal combustion engine. The carburetor uses a throttle valve to assist in metering liquid fuel and air flow to supply the varying engine fuel requirements during engine startup, idle, and steady-state operation. The throttle valve may rotate between idle and wide open positions to change the fluid flow rate in and through the carburetor.

SUMMARY

In at least some implementations, a charge forming device includes a body assembly including a main body that has a main bore through which fluid flows, a throttle valve and an adjuster. The throttle valve is carried by the body assembly and moveable relative to the main bore between a first position and a second position to control fluid flow through the main bore. The adjuster is slidably moveable relative to the throttle valve and engageable with the throttle valve to adjust the range of motion of the throttle valve between a third position and the second position.

In at least some implementations, the adjuster includes a secondary stop and the adjuster is moveable from a retracted position wherein the secondary stop does not interfere with throttle valve movement between the first position and the second position, and an advanced position wherein the secondary stop limits throttle valve movement between the third position and the second position. The range of motion of the throttle valve may be greater when the adjuster is in the retracted position, and/or the third position may be closer to the second position than is the first position. The adjuster may include a retainer to releasably retain the adjuster in the advanced position, and the retainer may be movable/releasable to permit the adjuster to move to the retracted position. In at least some implementations, the retainer includes a finger and a catch carried by the finger and adapted to engage a retaining surface carried by the body assembly, and the finger may be flexible so that the catch can move relative to the retaining surface. The adjuster may be carried in a void in the body assembly for slidable movement relative to the throttle valve, and the catch may be radially inwardly displaced when the adjuster is in the retracted position and move radially outwardly as the adjuster is moved to the advanced position to engage a retaining surface prevent movement of the adjuster to the retracted position. The throttle valve may include a cam that engages the retainer during movement of the throttle valve from the third position to the second position to release the retainer and permit the adjuster to move to the retracted position. A biasing member may yieldably bias the adj uster to the retracted position so that when the retainer is released the adjuster returns toward the retracted position under the force of the biasing member. In at least some implementations, a charge forming device includes a body assembly including a main body that has a main bore through which fluid flows and a retaining surface, a throttle valve carried by the main body and moveable relative to the main bore between a first position and a second position to control fluid flow through the main bore, and an adjuster. The adjuster has a secondary stop and a retainer, the adjuster is moveable relative to the throttle valve between retracted and advanced positions, and when adjuster is in the advanced position the secondary stop is engageable with the throttle valve to adjust the range of motion of the throttle valve between a third position and the second position, and when the adjuster is in the advanced position, the retainer is engaged with the retaining surface to maintain the adj uster in the advanced position. In at least some implementations, the throttle valve includes a cam that engages the retainer when the throttle valve is moved sufficient toward the second position to disengage the retainer from the retaining surface and permit the adjuster to move toward its retracted position. The retaining surface may be defined by a surface of the body assembly. The adjuster may be carried by the body for slidable movement relative to the throttle valve in a direction perpendicular to the axis of rotation of the throttle valve or within 20 degrees of perpendicular to the axis of rotation of the throttle valve.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of certain embodiments and best mode will be set forth with reference to the accompanying drawings, in which: FIG. 1 is a front view of a carburetor including a throttle valve adjuster;

FIG. 2 is a top view of the carburetor;

FIG. 3 is a left side view of the carburetor;

FIG. 4 is a front view of a throttle valve and the throttle valve adjuster with the a portion in section to illustrate certain features of the throttle valve adjuster;

FIG. 5 is a perspective view of a plate of the carburetor;

FIG. 6 is another perspective view of the plate;

FIG. 7 is a bottom view of throttle valve lever;

FIG. 8 is a perspective view of an adjuster body;

FIG. 9 is a side view of the adjuster body;

FIG. 10 is a top view of the throttle valve and adjuster in a first position of the throttle valve;

FIG. 11 is a front view of a throttle valve and the throttle valve adjuster in the first position;

FIG. 12 is a sectional view of the throttle valve and adjuster in the first position; FIG. 13 is a top view of the throttle valve and adjuster in a third position of the throttle valve;

FIG. 14 is a front view of a throttle valve and the throttle valve adjuster in the third position; and FIG. 15 a sectional view of the throttle valve and adjuster in the third position.

DETAILED DESCRIPTION

Referring in more detail to the drawings, FIGS. 1-3 illustrate a charge forming device 10 through which fuel, air or both are provided to an engine to support combustion within the engine. In the implementation shown, the charge forming device includes a carburetor 10 having a body assembly 11 that includes a main body 12 that has a main bore 14 through which fluid (air, fuel or both) flows. The body assembly 11 may also include one or more plates or other bodies carried by or mounted to the main body (e.g. plate 52 discussed later, and bodies 13, 15 which may define part of fuel metering and fuel pump assemblies, as is known in the art). Fluid flow through the main bore 14 is controlled at least in part by a throttle valve 16, which includes a throttle valve body 18 that is movable relative to the main bore 14 to vary fluid flow rate past the valve body 18. A source of fuel may be provided into the main bore 14, or downstream thereof, to be mixed with the air and delivered to the engine as a fuel and air mixture. In the implementation shown, the source of fuel includes a fuel metering chamber such as are commonly used in carburetors, but the fuel source could be a fuel injector or a fuel pump or other supply of fuel in a different device.

The main body 12 may be formed from one or more pieces of material and may be formed from metal or any other suitable material and by any desired process(es) such as but not limited to casting, machining or both. As shown in FIG. 2, the main bore 14 extends from an upstream side 22 of the main body 12 to a downstream side 24 of the main body 12 and may be of any size and shape desired. To mount and carry the throttle valve 16, the main body 12 may also include a throttle valve bore 32 (shown in dashed lines in FIG. 3). In the implementation shown, the valve bore 32 is located between the upstream side 22 and downstream side 24 of the main bore 14 and extends through and is generally perpendicular to the main bore 14, although other arrangements may be used.

The throttle valve 16 may include a cylindrical valve body 18 and may be rotated within the valve bore 32 relative to the main body 12. A throttle opening 34 extends through the throttle valve body 18 and is increasingly aligned with the main bore 14 as the throttle valve 16 is rotated from a first position to a second position. This type of throttle valve 16 is sometimes called a rotary throttle valve. In other implementations, the throttle valve may be a butterfly type valve with a butterfly type valve head including a disc fixed to a valve shaft to rotate with the valve shaft relative to the main bore 14 between first and second positions. In the first position the throttle valve 16 may provide more resistance to fluid flow through the main bore 14 than when the throttle valve 16 is in its second position. In at least some implementations, the first position may be associated with idle engine operation (e.g. the lowest speed and load engine operation) and may permit a relatively low flow rate of fluid past the valve head. The second position of the throttle valve 16 may be associated with wide open engine operation (e.g. highest speed and/or load engine operation) and in that position, the throttle valve 16 permits a greater flow rate of fluid through the main bore 14. The throttle valve 16 may be moved to any position between the first and second positions to provide a desired fluid flow rate from the main bore 14 and to the engine.

As shown in FIGS. 1-4, 7, 10, 1 1, 13 and 14, to control rotation of the throttle valve 16, the throttle valve 16 may include a throttle lever 40 coupled to the valve body 18 and accessible from outside of the main body 12. A tab 42 extending from the throttle lever 40 may include a coupler 44 or otherwise be coupled to a control cable 46 (shown in dashed lines in FIG. 2) that is operable to rotate the throttle valve 16 from its first position toward or to its second position. A return actuator such as a spring, may automatically return the throttle valve 16 to its first position when the cable 46 is not providing a force acting on the throttle lever 40. Of course, other actuators can be used and the cable and spring implementation is not limiting to the possibilities of actuators. The actuators may include, again without intending to limit disclosure to any particular implementation, one or more solenoids, servomotors, springs or other devices or manually manipulated levers, dials or the like.

The first position of the throttle valve 16 may be defined by an idle stop or stop surface 48 carried by or formed on the main body 12 (e.g. a separate component coupled to the main body 12 or a feature defined integrally in the main body 12 itself). In the implementation shown (e.g. in FIGS. 1 -6), the stop surface is defined by a pin 48 carried by a flange 50 extending from a plate 52 that is fixed to the main body 12. The pin 48 extends outwardly from the plate 52 so that an end of the pin is in the path of rotation of the throttle valve 16. The pin 48 may be moved relative to the plate 52 so that the position of the end of the pin is adjustable to vary the angular position of the throttle valve 16 in the first position as desired. The position of the pin 48 may be calibrated for a particular carburetor or throttle body and then the position can be locked in place, if desired. In the implementation shown, the pin 48 is threaded and engaged with threads in a bore of the plate 52 so that the pin 48 may be advanced and retracted by rotating the pin 48 relative to the plate. Of course, the pin 48 may be adjustable to permit tuning of the carburetor 10 after assembly and use on an engine, if desired. The throttle valve 16 is shown in its first position in FIGS. 1-4 and 10-12.

To permit selective control of the throttle valve position, a valve adjuster 54 may be associated with the throttle valve 16. In at least some implementations, the valve adjuster 54 may establish a third position of the throttle valve 16, such as is shown in FIGS. 13-15. The third position of the throttle valve 16 may be between the first position and the second position of the throttle valve 16 to provide the throttle valve 16 in a more open position than the first position at idle/low speed and low load operation, and thereby permit a greater fluid flow rate through the main bore 14. In at least some implementations, the third position of the throttle valve 16 is rotationally closer to the first position than the second position and defines an off-idle or fast-idle position for the throttle valve 16. Hence, when the valve adjuster 54 is actuated the throttle valve 16 may rotate between the third and second positions. Some situations where it may be desirable to operate the throttle valve 16 between the third and second positions include (but are not limited to) during restarting of a hot engine and during starting of a cold engine.

In at least some implementations the adjuster 54 may include a body 55 (shown by itself in FIGS. 8 and 9) that defines a secondary stop 56 and is movably carried by the carburetor for selective engagement with the throttle lever 40. The adjuster 54 may be movable from a first or retracted position wherein the adjuster does not engage the throttle lever 40 or another part of the throttle valve 16, and a second or advanced position in which the adjuster does engage the throttle lever 40 or other part of the throttle valve 16 to position the throttle valve in the third position. In the example shown the adjuster 54 includes a projection 58 defining the secondary stop 56 that engages the throttle lever tab 42 when the adjuster is in the advanced position (e.g. a skirt or wall 59 depending from and/or part of the tab 42 as shown in FIGS. 7, 12 and 15— in FIGS. 12-15, the throttle lever is shown in section with the wall 59 remaining in view) and which is spaced from the path of movement of the tab 42 when the adjuster is in the retracted position. In at least some implementations, the adjuster 54 is slidably carried by the plate 52 so that the adjuster is movable relative to the throttle valve 16, and the adjuster may move linearly relative to the plate along a central axis of the adjuster or other path of motion. In the implementation shown, the adjuster 54 is received within a void 60 in the plate 52 and is slidable within the void relative to the plate and the throttle valve 16. The void 60 may be of any desired shape and the adjuster 54 may be constructed for use with any desired void. In the implementation shown, the void 60 is generally cylindrical and the adjuster 54 is moved along an axis 62 of the void. The adjuster 54 may have an exterior surface 64 that may be manually or otherwise engaged to axially move (e.g. push) the adjuster from its retracted position to its advanced position to advance the secondary stop 56 into the path of movement of the throttle valve 16 (e.g. a portion of the lever 40). Movement of the adjuster 54 toward the throttle valve 16 may be limited by engagement with a stop, if desired. As shown in FIG. 4, a pin 63 extends through an opening 65 in the plate 52 so it may engage the adjuster 54 to limit advancement of the adjuster 54. A head 67 of the adjuster body 55 may instead or additionally engage a flange 69 or the plate 52. Of course, the adj uster 54 may be otherwise moved between its positions, for example, by rotation relative to the plate 52 where the adjuster and plate have mating threads or the like that cause axial or longitudinal movement of the adjuster as it is rotated.

To retain the adjuster 54 in the advanced position so that it need not be manually held in that position, the adjuster or carburetor 10 may include a retainer 66 to releasably retain the adjuster in its advanced position. In the example shown, the retainer 66 includes a flexible finger 68 with a catch 70 having an engagement surface that is not parallel to the axis 62 along which the adjuster 54 moves. As shown in FIGS. 12 and 15, the catch 70 is perpendicular to the direction of movement of the adjuster 54 between its retracted and advanced positions. The retainer 66 may be yieldably biased so that the catch 70 moves radially relative to the axis 62 and may be received within the void 60 when the retainer is retracted and moves radially outwardly to overlap a retaining surface 72 (e.g. of the plate 52 or carburetor body 12) when the catch 70 is moved out of the void 60. In this way, the catch 70 engages the retaining surface 72 to limit or prevent movement of the adjuster 54 back toward its retracted position. To facilitate release of the retainer 66 and movement of the adjuster 54 back to its retracted position, a biasing member 74 may be provided that yieldably biases the adjuster 54 toward its retracted position. In the embodiment shown, the biasing member is a spring 74 and provides a force that acts axially on the adjuster 54 to axially displace the adjuster within the void 60, although other arrangements may be used. The biasing member 74 tends to keep the catch 70 engaged with the retaining surface 72 to provide a consistent location of the adjuster 54 and the secondary stop 56 in the advanced position of the adjuster. The biasing member 74 also urges and moves the adjuster 54 toward or to its retracted position when the catch 70 is not engaged with the retaining surface 72. The pin 63 may limit movement of the adjuster body 55 away from the throttle valve 16 and retain the adjuster body 55 in the void 60.

To release the retainer 66 and permit the adjuster 54 to return to its retracted position when desired, the catch 70 is displaced from the retaining surface 72 and the biasing member 74 moves the adjuster back to the retracted position. This may be done manually, or automatically. An example of a manual release of the retainer 66 is with an adjuster that is rotatable, wherein manual rotation of the adjuster to retract the adjuster could move the catch into engagement with a cam that radially displaces the catch so that it may be received within the void upon further retraction of the adjuster. An example of an automatic release is shown in the drawings, particularly in FIGS. 10-15, wherein actuation of the throttle valve 16 toward its second position (counterclockwise in FIGS. 12 and 15) causes a cam 76 to engage and displace the catch 70 from the retaining surface 72 by increasingly radially inwardly flexing the finger 68 as the throttle valve 16 is rotated. When, due to this flexing of the finger 68, the catch 70 is clear of the retaining surface 72, the biasing member 74 displaces the adjuster 54 toward its retracted position wherein the catch is received within the void 60 and is axially spaced from and not engaged with the retaining surface 72. This also moves the secondary stop 56 out of the path of the throttle valve 16 so that the throttle valve can be returned to its first position, that is, the throttle valve may move past the third position to engage the idle stop 48 when the adjuster 54 is retracted. The cam 76 may be carried by the throttle valve body 18 or lever 40 so that the cam is moved relative to the catch 70 as the throttle valve 16 rotates. When the throttle valve 16 is in the third position, the cam 76 is spaced from the catch 70 by a desired amount to control the amount of throttle valve movement toward the second position that is needed to release the adjuster 54.

The adjuster 54 will normally be actuated prior to starting an engine. Hence, the throttle valve 16 will be in the first position and actuation of the adjuster will move the throttle valve away from its first position and into its third position before the engine is started. In this way, the adjuster 54 is operable to limit the range of rotation of the throttle valve 16 between a third position and a second position. In at least some implementations, the third position is closer to a wide open throttle position than is the first position, although this is not necessary. The adjuster 54 may be used temporarily during a period of engine operation (e.g. to facilitate re-starting a hot engine) or for the entire engine operation (e.g. to facilitate engine operation at higher altitudes than that for which the engine was calibrated). Thus, the engine may be operated in two modes: a first mode wherein the throttle valve 16 may move between a first position and a second position; and a second mode wherein the throttle valve 16 may move between a third position and the second position.

In at least some implementations, the third position of the throttle valve 16 may be offset from the first position by about 0.25 to 25 degrees of rotation of the throttle valve 16, which results in the throttle valve 16 being more open when in the third position than when in the first position. In at least some charge forming devices, in the first position, the throttle valve 16 might be rotated 5-30 degrees relative to a plane that is perpendicular to an axis 80 (FIG. 3) of the main bore 14 so that the throttle valve 16 is slightly open relative to the main bore 14 and fluid may flow through the main bore 14. Therefore, in the third position, the throttle valve 16 may be rotated about 5.25 to 55 degrees or so relative to that plane so that the throttle valve 16 is more open and a greater fluid flow rate is permitted through the main bore 14.

The rotation of the throttle valve 16 is usually also accompanied by an axial movement of the throttle valve as caused by a cam surface engaged by the throttle valve to increase a flow area of a fuel port, as is known in the art for example in USPN 7,287,741 (where the cam is associated with the throttle valve lever) and USPN 7,290,757 (where the cam is associated with the throttle valve body) each of which is incorporated herein by reference in its entirety. In the implementation shown, the cam surface 82 is defined on the throttle valve lever 40 as shown in FIG. 7 and is adapted to engage a follower (e.g. a ball) carried in a boss 84 (FIG. 5) on the plate 52. The cam surface is axially inclined so rotation of the throttle valve causes axial movement of the valve body relative to the carburetor body 12 and plate 52. Movement of the adjuster 54 can be implemented so that the throttle valve 16 is rotated and remains engaged with the cam surface 82 or so that the throttle valve is displaced axial an amount controlled by the cam surface 82 in accordance with the magnitude of throttle valve rotation. Movement of the adj uster 54 can also lift or axially displace the throttle valve 16 to increase fuel flow beyond the amount otherwise determined by the cam surface 82, and this axial throttle valve movement can be independent of or accompanied by some throttle valve rotation, as desired. In the implementation shown, the axis 62 along which the adj uster 54 moves is perpendicular to the rotational axis 88 of throttle valve 16 and rotates the throttle valve without displacing the throttle valve off of the cam surface 82. In other implementations, the adjuster is carried by the body for slidable movement relative to the throttle valve in a direction perpendicular to the axis of rotation of the throttle valve or within 20 degrees of perpendicular to the axis of rotation of the throttle valve. Also in the implementations shown, the adjuster slides in and relative to the void between the retracted and extended positions, and the secondary stop is moved closer to an axis of rotation of the throttle valve when the adjuster is moved toward the advanced position.

While the forms of the invention herein disclosed constitute presently preferred embodiments, many others are possible. It is not intended herein to mention all the possible equivalent forms or ramifications of the invention. It is understood that the terms used herein are merely descriptive, rather than limiting, and that various changes may be made without departing from the spirit or scope of the invention.