Power equipment with throttle release actuator

An outdoor power tool may include an engine, a carburetor configured to provide a fuel and air mixture to the engine based on operation of a throttle assembly, a selector and a throttle release actuator. The selector may be operably coupled to the throttle assembly to control a position of the throttle assembly in a selected one of a plurality of throttle positions. One of the throttle positions may be an idle position and each of the other throttle positions may be selectable by an operator via manual positioning of the selector. The throttle release actuator may be configured to return the selector from any one of the throttle positions to the idle position responsive to operator actuation of the throttle release actuator.

TECHNICAL FIELD

Example embodiments generally relate to outdoor power equipment and, more particularly, relate to outdoor power equipment devices that employ carburetors in connection with internal combustion engines.

BACKGROUND

Outdoor power equipment includes such devices as mowers, trimmers, edgers, chainsaws, blowers and the like. These devices are often used to perform tasks that inherently require the devices to be mobile. Accordingly, these devices are typically made to be relatively robust and capable of handling difficult work in hostile environments, while balancing the requirement for mobility.

Powering such devices could be accomplished in any number of ways. However, for outdoor power equipment that is intended to be handheld, size and weight become important considerations. Thus, one common source of power for handheld outdoor power equipment has been the internal combustion engine due to its ability to provide ample power in a relatively small package. Internal combustion engines for handheld outdoor power equipment typically employ engines that blend air and fuel in a carburetor. The carburetor is a well known device, and employs an internal venturi to enable airflow provided into the engine to draw fuel into the airstream. In many cases, the flow of air and fuel into the engine can be controlled using a throttle valve.

In some engines, the position of the throttle valve may be adjusted by an operator employing some form of trigger mechanism, usually coupled to the throttle valve via a cable. The trigger mechanism may be provided on a handle of the machine so that it can be operated by a hand or fingers of the operator. In such an engine, when the trigger mechanism is not depressed, the engine is typically enabled to return to an idle condition. However, not all engines are necessarily constructed to employ trigger mechanisms. Some engines employ a series of discrete throttle valve positions that are manually selectable to increase the simplicity of design. In such designs, a lever or selector is typically adjusted manually by the operator to one of the throttle valve positions. Movement between each of these positions therefore requires the operator to manually select a desired position, including the idle position.

BRIEF SUMMARY OF SOME EXAMPLES

Some example embodiments may therefore provide a throttle release actuator that is configured to enable a user to easily return the engine to an idle state. In this regard, a lever or selector may be provided that is enabled to be manually moved to any one of a number of selectable throttle positions. However, the operator may be further enabled to trigger an automatic return to the idle position from any one of the selectable throttle positions via a single return mechanism in the form of the throttle release actuator.

According to an example embodiment, an outdoor power tool may be provided. The outdoor power tool may include an engine, a carburetor configured to provide a fuel and air mixture to the engine based on operation of a throttle assembly, a selector and a throttle release actuator. The selector may be operably coupled to the throttle assembly to control a position of the throttle assembly in a selected one of a plurality of throttle positions. One of the throttle positions may be an idle position and each of the other throttle positions may be selectable by an operator via manual positioning of the selector. The throttle release actuator may be configured to return the selector from any one of the throttle positions to the idle position responsive to operator actuation of the throttle release actuator.

In accordance with another example embodiment, a method of assembling a throttle release actuator is provided. The method may include an operation of providing a support assembly proximate to a shaft of a throttle assembly. The shaft may operably couple a selector to a throttle valve of the throttle assembly for selection of a position of the throttle valve based on manual positioning of the selector in a selected one of a plurality of throttle positions. The method may further include an operation of providing a biasing assembly into a portion of the selector. The biasing assembly may be configured to return the selector to an idle position from any one of the throttle positions responsive to operation of the throttle release actuator. The method may further include an operation of inserting the selector into a window defined in a cap structure of the throttle release actuator while compressing the biasing assembly to enable the biasing assembly to fit within the window. The window may enable rotation of the selector about an axis defined by the shaft to the throttle positions. The method may further include an operation of attaching the cap structure to the support assembly.

Some example embodiments may provide an operator of an outdoor power tool with improved ability to return of the tool to an idle state while operating the tool. Thus, for example, during operation in a state other than the idle state, if the operator should for any reason desire or need to return to the idle state, the return may be conducted without manual interaction between the operator and the selector.

DETAILED DESCRIPTION

Some example embodiments described herein provide a throttle release actuator that is usable with any of a variety of devices that are examples of outdoor power equipment. In particular, some embodiments may form a throttle release assembly that is configured to enable a user to easily return the engine to an idle state. In this regard, a lever or selector may be provided that is enabled to be manually moved to any one of a number of selectable throttle positions. However, the operator may be further enabled to trigger an automatic return to the idle position from any one of the selectable throttle positions via actuation of the throttle release actuator.

FIG. 1illustrates a perspective view of a blower100. It should be appreciated that the blower100ofFIG. 1merely represents one example of power equipment on which an example embodiment may be employed. Thus, alternative embodiments may also be employed on other devices such as, for example, trimmers, edgers and/or the like. The blower100is therefore only presented as one, non-limiting example for which some of the functionality achievable by example embodiments will be described.

Referring toFIG. 1, the blower100may include a housing110inside which a power unit or engine120is housed. In some embodiments, the power unit may be an internal combustion engine employing a carburetor. The blower100may further include a blower tube130that is attached to housing110and through which air may be expelled. The operation of the engine120may cause an impeller (not shown) to rotate so that air can be drawn into the blower100and expelled from the blower tube130to blow leaves, debris, or any other desirable material. The blower100may further include a selector140that may be operably coupled to a throttle valve that controls the provision of air through the carburetor.

In an example embodiment, the selector140may be a lever, switch, or other member that is provided to be selectable between a plurality of different positions. In a typical embodiment, the selector140must be manually moved by the operator to each and every one of the selectable different positions in order to affect the selection of a corresponding one of those different positions. In other words, there is no mechanism provided to move from any one of those positions to another of those positions without the operator physically handling the selector140to move the selector and cause the corresponding different position to be selected. Thus, for example, if an operator is operating in a selected one of the different positions, there is no way to return to an idle state unless the operator manipulates the selector to the idle state.

However, in accordance with an example embodiment, return to the idle state may be accomplished from any one of the selected positions automatically responsive to the operator triggering operation of a throttle release actuator according to an example embodiment. As such, for example, after the operator actuates the throttle release actuator, regardless of the position in which the selector140is initially fixed, the selector140will be returned to the idle position so that the engine120returns to the idle state without requiring the operator to operate (or in some cases even touch) the selector140.FIGS. 2 to 5illustrate one example of how the throttle release actuator of one example embodiment may be provided.

FIG. 2, which includesFIGS. 2A and 2B, shows respective different perspective views of a carburetor200with a throttle release actuator240that may be employed in the blower100or some other device.FIG. 3, which includesFIGS. 3A and 3B, shows respective different exploded perspective views of the throttle release actuator240in accordance with an example embodiment.FIG. 4, which includesFIGS. 4A, 4B and 4C, illustrates a top perspective view, a bottom perspective view, and a bottom perspective view with biasing element installed of the selector210of an example embodiment.FIG. 5illustrates a side view of the selector and throttle release actuator of one example embodiment in which the throttle release actuator and selector are meant to be transparent to reveal the biasing element in situ according to an example embodiment.

An example embodiment will now be described in reference toFIGS. 2 to 5. As is conventionally known, air and fuel are mixed in the carburetor200for provision to the engine120for combustion therein. Air may be provided via an air inlet202and the fuel may be provided via a fuel inlet204. A venturi may be provided at an interior of the carburetor200to draw fuel into the carburetor200for mixing with the air. A selector210of an example embodiment may be provided to be operably coupled to a throttle assembly. The throttle assembly may include a rotatable shaft that is operably coupled to a throttle valve220and the selector210. InFIG. 2, the rotatable shaft is not visible, but is located within a support assembly230that is fixed to a portion of the carburetor200(and is labeled as shaft260inFIGS. 3 and 5).

Based on the positioning of the selector210, the throttle valve220may be positioned and a corresponding amount of air may be provided through the carburetor200. As the amount of air is allowed to increase, more fuel will be drawn into the mixture and passed into the engine120. When the selector210is in an idle position, a relatively low amount of air may be permitted to pass by the throttle valve220and the engine120may operate in an idle state. As the selector210is moved to subsequent other operating positions, which may correlate to distinct or discrete different positions of the selector210, the throttle valve220is opened further and increased air flow is permitted (which draws correspondingly increased fuel into the carburetor200).

According to an example embodiment, the selector210may be automatically returned (i.e., returned without the operator having to manually grasp and reposition the selector210) by operation of a throttle release actuator240. The throttle release actuator240may be an assembly that is defined by a cap structure242that has a rest position and a depressed position, and a biasing assembly250that is configured to work with the cap structure242, the selector210and/or the support assembly230to perform the automatic return of the selector210in accordance with an example embodiment. In the rest position, which is shown in the example ofFIG. 5, the cap structure242may be in its normal position and may be held in such position by the biasing assembly250(in connection with structural elements of the cap structure and support assembly230as described in greater detail below). The biasing assembly250of an example embodiment may have dual functionality of biasing the cap structure242toward the normal position and biasing the selector210toward the idle position. When deflected or otherwise moved out of the positions toward which the biasing assembly250is biased, corresponding components may overcome the biasing force of the biasing assembly250to enable the cap structure242and the selector210to be respectively moved out of the normal positions toward which they are biased (i.e., the rest position and the idle position, respectively). Thus, for example, when the cap structure242is depressed to actuate the throttle release actuator240, the cap structure is moved downward (as shown by arrow244) and the biasing assembly250is charged or loaded to enable the biasing assembly250to unload or discharge (moving in the direction shown by arrow246) to return the cap structure242to its rest position after the cap structure242is no longer depressed. Similarly, as will be described in greater detail below, when the selector210is moved to overcome the force of the biasing assembly250that tends toward returning the selector210to the idle position, the biasing assembly250may be charged or loaded to enable the biasing assembly250to unload or discharge and return the selector210to the idle position when (as will be discussed in greater detail below) the cap structure242is in the depressed state.

In an example embodiment, the selector210may be provided with a lever arm212and a main body214. The main body214may be substantially cylindrical in shape with a diameter of the main body214being slightly less than an inner diameter of the cap structure242so that the cap structure242is enabled to receive the main body214therein. The main body214may also have one or more structures provided therein to facilitate housing and/or operation of the biasing assembly250and also to facilitate reception of the shaft260to which the throttle valve220may be operably coupled. In an example embodiment, the main body214may include a reception slot216that is shaped to receive a key portion262disposed at a distal end of the shaft260. The reception slot216may engage the key portion262such that rotation of the lever arm212causes the main body214to rotate about an axis defined by the shaft260and also causes the shaft260to rotate accordingly. It should also be appreciated that a slot could be provided on the shaft260and a corresponding keying structure could be provided on the main body214in some alternative embodiments.

The cap structure242of some embodiments may include a substantially continuous top portion having a circular shape. This top portion may form a “button” that can be depressed by the operator. The cap structure242may also have a substantially cylindrical shape formed by sidewalls that extend from circumferential edges of the top portion. In some embodiments, these sidewalls may have openings formed therein. For example, the cap structure242of an example embodiment may include a first window247and a second window248. The first window247may receive the main body214during assembly such that the lever arm212passes through the first window247and enables the main body214to rotate about the axis defined by the shaft260when the lever arm212is grasped and moved by the operator. In some cases, a protrusion218may extend radially outwardly from a sidewall of the main body214out the second window248. Although not required, the sidewall from which the protrusion218extends may be a sidewall that is substantially opposite to the sidewall from which the lever arm212extends. The protrusion218may be configured or shaped to facilitate engagement with a selected one of various reception slots249defined in the second window248of the cap structure242.

During operation, the operator may rotate the lever arm212and the protrusion218may ride along a surface of the second window249to a selected one of the reception slots249. As indicated above, the movement of the lever arm212away from the idle position may charge the biasing assembly250. However, when the protrusion218is allowed to settle into one of the reception slots249, the mechanics of the engagement therebetween (and/or the friction associated with the engagement) may be sufficient to prevent the biasing assembly250from returning the selector210to the idle position. However, if the cap structure242is pushed in the direction shown by arrow244, the protrusion218may be lifted out of the respective one of the reception slots249so that the biasing assembly250is free to act upon the selector210to return it to the idle position.

It should be noted that the examples ofFIGS. 2 to 5are merely illustrative of one way to implement an example embodiment. Thus, for example, in some embodiments, the cap structure242may carry a protrusion, and a plurality of discrete slots, detents or catches may be provided on the main body214to accomplish similar functionality. Moreover, in some alternatives there need not necessarily be a plurality of discrete reception slots, catches or detents to define corresponding specific throttle positions. Instead, the plurality of positions at which the selector210may be held away from the idle position may be non-discrete locations. In such an embodiment, the friction between the cap structure242and the main body214may be sufficiently provided (by any means) to prevent the biasing assembly250from overcoming the friction and returning the selector210to the idle position except when the cap structure242is depressed.

In an example embodiment, the biasing assembly250, as indicated above, may have dual functions of providing for restoration of the cap structure242to the rest position after it is depressed and restoration of the selector210to the idle position responsive to depression of the cap structure242(i.e., actuation of the throttle release actuator240). The dual functions may, in some embodiments, be performed by separate and distinct components (i.e., separate biasing elements). For example, a torsion spring or the like may be provided to be supported by the shaft260and fixed at one end within the selector210and fixed at the opposite end by a portion of the support assembly230to handle return of the selector210, while a compression spring or the like is provided to compress between the cap structure242and a portion of the support assembly230(or a portion of the shaft260or the selector210) to return the cap structure242to the rest position after it has been depressed. However, in an example embodiment (such as is shown inFIGS. 2-5), the biasing assembly250may be provided as a single unitary biasing element that has a torsion portion and a compression portion to perform both of the functions described above.

In an example embodiment, the compression portion of the biasing assembly250may extend from the selector210to an interior portion of the cap structure242to push (e.g., in the direction of arrow246) the cap structure242away from the selector210. Meanwhile, the torsion portion may be provided such that the torsion portion extends around the shaft260and one end thereof is abutted against or held within a slot270within the main body214and the other end thereof is abutted against a post272of the support assembly230. The post272may be proximate to the shaft260(although it need not be), and may extend away from a base portion of the support assembly230in an axial direction (e.g., a direction substantially parallel to the axis defined by the shaft260). Accordingly, for example, as the selector210is moved by the operator, a channel274in the main body214of the selector210may accommodate or receive the post272over the range of motion of the selector210. The selector210may then be held in a particular throttle position while the torsion portion is charged and ready to return the selector210to the idle position when the cap structure242is depressed to overcome the friction (or mechanical block) that prevents the selector210from returning to the idle position when the cap structure242is in the rest position.

Thus, for example, the compression portion may exert a linear force that is in the axial direction (substantially parallel to the axis defined by the shaft260) in the direction shown by arrow246. Meanwhile, the torsion portion may exert a rotary force that is in a second direction that is tangential to a radial direction (i.e., tangential to the circumference of the main body214) where the radial direction is substantially parallel to a radius of the shaft260. Although the torsion portion and compression portions of the examples pictured are provided by coil springs, it should be appreciated that other structures could alternatively be employed. For example, plastic or elastic materials having movable components that tend to resist movement and restore themselves in response to such movement may alternatively be employed in some cases. In an example embodiment, a living hinge may be employed for either or both of the compression portion or the torsion portion of the biasing assembly250.

In some embodiments, the support assembly230may include a substantially cylindrically shaped selector receiver portion280onto or into which the cylindrical main body214of the selector210may be received. Sidewalls of the cap structure242may then extend along the selector receiver portion280(and in some cases also the main body214) to encapsulate or enclose the main body portion214between the cap structure242and the selector receiver portion280. In some embodiments, the cap structure242may have a lip282that can slide over a bottom edge of the selector receiver portion280and then engage the selector receiver portion280when the cap structure242is fully installed. The lip282may engage the bottom edge of the selector receiver portion280when the cap structure242is in the rest position, but may not engage the selector receiver portion280when the cap structure242is depressed.

In some cases, the selector receiver portion280may include a key structure284to hold the cap structure242in alignment with the selector receiver portion280via reception of the key structure284in a keying slot286disposed at an internal portion of the cap structure242. Although not required, the keying slot286may be disposed on a same side of the cap structure242on which the second window248is located. It should also be appreciated that other keying structures could be employed, and the key portion and slot portion of such structures could be alternately placed on either of the two components being held together.

As indicated above, the lever arm212may extend through the first window247. Accordingly, care must be taken to ensure proper assembly of the throttle release actuator. A method of assembling a throttle release actuator in accordance with an example embodiment is therefore also provided as shown in the block diagram ofFIG. 6. The method may include providing a support assembly proximate to a shaft of a throttle assembly at operation300. The shaft may operably couple a selector to a throttle valve of the throttle assembly for selection of a position of the throttle valve based on manual positioning of the selector in a selected one of a plurality of throttle positions. The method may further include providing a biasing assembly into a portion of the selector at operation310. The biasing assembly may be configured to return the selector to an idle position from any one of the throttle positions responsive to operation of the throttle release actuator. The method may further include inserting the selector into a window defined in a cap structure of the throttle release actuator while compressing the biasing assembly to enable the biasing assembly to fit within the window at operation320. The window may enable rotation of the selector about an axis defined by the shaft to the throttle positions. The method may also include attaching the cap structure to the support assembly at operation330.

As can be appreciated from the description above, some embodiments may be enabled to provide improved control over outdoor power equipment that does not employ a trigger mechanism that automatically returns the engine to idle after release of the trigger. Thus, for example, even for machines with relatively simple controls, an improved amount of control over the operation of the machine can be provided to the user. Accordingly, some example embodiments may provide an ability to meet applicable operation standards or simply improve operator satisfaction with the control and operability of outdoor power equipment that is used or purchased.

According to an example embodiment, an outdoor power tool may be provided. The outdoor power tool may include an engine, a carburetor configured to provide a fuel and air mixture to the engine based on operation of a throttle assembly, a selector and a throttle release actuator. The selector may be operably coupled to the throttle assembly to control a position of the throttle assembly in a selected one of a plurality of throttle positions. One of the throttle positions may be an idle position and each of the other throttle positions may be selectable by an operator via manual positioning of the selector. The throttle release actuator may be configured to return the selector from any one of the throttle positions to the idle position responsive to operator actuation of the throttle release actuator.

The power tool of some embodiments may include additional features that may be optionally added either alone or in combination with each other. For example, in some embodiments, (1) the throttle release actuator may include a biasing assembly operably coupling the selector to a support assembly provided on the carburetor. The biasing assembly may be biased to return the selector to the idle position without operator contact with the selector. In some cases, (2) the biasing assembly may operate in a first direction to reset a position of the throttle release actuator responsive to actuation of the throttle release actuator and operate in a second direction to return the selector to the idle position responsive to actuation of the throttle release actuator. In an example embodiment, (3) the first direction is an axial direction and the second direction is tangential to a radial direction. In some embodiments, (4) the first direction is an axial direction and the second direction is tangential to a radial direction. In some cases, (5) the torsion portion and the compression portion are provided in a single unitary biasing element. In an example embodiment, (6) the torsion portion and compression portion are provided by separate springs. In some cases, (7) the throttle positions are discrete positions and the throttle release actuator may be defined by a cap structure into which the selector is provided. The cap structure may define a plurality of reception slots, each of which corresponds to one of the discrete positions. The selector may include a protrusion that is extendable into any one of the reception slots to define a reception slot into which the protrusion extends as the selected one of the throttle positions. In some embodiments, (8) the throttle positions are non-discrete positions and the throttle release actuator may be defined by a cap structure into which the selector is provided. The selector may include a protrusion that contacts the cap structure over a range of the non-discrete positions to define an intersection of the protrusion with the cap structure as the selected one of the throttle positions.

In some embodiments, any or all of the items (1) to (8) above may be provided individually or in combination with each other and the cap structure of the throttle release actuator may be depressed to actuate the throttle release actuator to enable movement of the protrusion from the selected one of the throttle positions to the idle position based on operation of a dual function biasing element that is biased both to return the selector to the idle position and return the throttle release actuator responsive to release of the throttle release actuator after the throttle release actuator is depressed. Additionally or alternatively, any or all of the items (1) to (8) above may be provided individually or in combination with each other and the cap structure may be enabled to move in an axial direction along an axis defined by a shaft of the throttle assembly that couples the selector to a throttle valve of the throttle assembly, but not to rotate about the axis. The selector may be enabled to rotate about the axis to each of the throttle positions, but not to move in the axial direction. Additionally or alternatively, any or all of the items (1) to (8) above may be provided individually or in combination with each other and the selector may be received in a first window of the cap structure and the reception slots or non-discrete positions are disposed in a second window of the cap structure. Additionally or alternatively, any or all of the items (1) to (8) above may be provided individually or in combination with each other and the selector may be provided with a biasing element that is compressed in an axial direction to enable the selector and the biasing element to be provided in the first window.