Patent Description:
Typically, prime movers such as motors and engines are connected to output shafts of machines through one or more meshing interfaces which selectively transmit power from the prime mover to the output shaft. These meshing interfaces allow the prime mover to selectively propel the machine. For example, meshing interfaces between one or more driving motors and one or more wheels of a lawnmower may allow an operator to selectively drive the wheels of the lawnmower. Similarly, meshing interfaces between one or more driving motors and one or more cutting blades of the lawnmower may allow the operator to selectively drive the cutting blades. <CIT> discloses a clutch, comprising a clutch weight assembly, a main driving assembly, a plurality of corotating elements, and a base plate. The main driving assembly will be rotated when the power source is activated, and the corotating elements are driven synchronously to rotate and then the clutch weight assembly will be driven to rotate synchronously by the corotating elements. When the speed of the rotation is high enough and the centrifugal force of clutch weight is strong enough to overcome the inward bending strength of the flexible component of the clutch weight assembly, then the clutch weight will fly outward to grab the driven part to proceed the slippery engagement. When the friction resistance between the wear pad of the clutch weight and the driven part is greater than the predetermined transformable strength of the corotating element to make the engagement between the wear pad of the clutch weight and the driven part, the power is efficiently transmitted to the driven part. <CIT> shows a lawn mower with an automatic clutch, which has a shell, one or more blades pivotally installed in the shell, an engine in the shell for driving the blades to cut grass, a self-propelled motor in the shell, a retarding mechanism fixed with respect to the self-propelled motor, a self-propelled shaft driven by the retarding mechanism, a pair of rear wheels driven by the self-propelled shaft, a pair of front wheels on a front portion of the shell, a handle on a rear portion of the shell, a power, a control mechanism on the handle, and an automatic clutch provided between the self-propelled motor and the retarding mechanism. The automatic clutch has a tubular shell, an output shaft, a pair of symmetric block, a pair of elastic elements, an input shaft, and a crow block. <CIT> discloses a hydraulic pump for an automobile, which is capable of changing slow and fast rotational speeds corresponding to an engine rotation speed by a simple constitution, and achieving compactness. Between an input shaft from an engine and a rotor shaft, a planetary speed increaser is provided to increase the rotational speed of the input shaft to be transmitted to the rotor shaft. A centrifugal clutch to directly couple the input shaft and the rotor shaft by action of centrifugal force in accordance with rotation of the input shaft, and a one-way clutch provided to act to disconnect transmission by the planetary speed increaser, when the input shaft is directly coupled with the rotor shaft by connection of the centrifugal clutch, are provided. Inhibition of slow rotation of the rotor shaft when directly coupled with the input shaft is thus intended to be eliminated.

Meshing interfaces typically utilize a user engageable element which allows a user to directly or indirectly affect the interface. For instance, a clutch fork or other user engageable element may allow the operator to selectively engage and disengage the clutch mechanism. These types of interfaces allow the operator to engage the meshing interface. However, these interfaces require user input to operate.

Accordingly, improved clutch mechanisms are desired in the art. In particular, clutch mechanisms which provide simple, cost effective, space-efficient operation would be advantageous. Advantageous examples are the subject matter of the dependent claims.

Aspects and advantages of the invention in accordance with the present disclosure will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the technology.

According to the present invention, a transmission is provided. The transmission includes an input comprising an input gear; an output; a centrifugal clutch mechanism that transfers energy from the input to the output, the centrifugal clutch mechanism comprising: a disk having an outer gear that meshes with the input gear; centrifugal weights movably coupled to the disk; and a central shaft rotatable relative to the disk and extending through the disk, the central shaft comprising drive surfaces, wherein the disk is rotatably coupled to the input, wherein the output is rotatably coupled to the central shaft, wherein the centrifugal weights rotate between a disengaged position in which the centrifugal weights do not interface with drive surfaces and an engaged position in which the centrifugal weights interface with the drive surfaces, and wherein the centrifugal weights are disposed inside the perimeter of the disk when the centrifugal weights are in the engaged position.

In accordance with the present invention, a centrifugal clutch mechanism is provided. The centrifugal clutch mechanism includes a disk having a perimeter; centrifugal weights movably coupled to the disk; a central shaft rotatable relative to the disk and disposed between the centrifugal weights, the central shaft comprising drive surfaces, wherein the disk comprises an outer gear configured to be rotated by an input, wherein the central shaft is configured to rotate an output, wherein the centrifugal weights rotate between a disengaged position in which the centrifugal weights do not interface with drive surfaces and an engaged position in which the centrifugal weights interface with the drive surfaces, and wherein each of the centrifugal weights is compressed between an outer surface of the disk and the drive surfaces of the central shaft when the centrifugal weights are in the engaged position.

In accordance with another embodiment, a centrifugal clutch mechanism is provided. The centrifugal clutch mechanism includes a disk having a perimeter; centrifugal weights movably coupled to the disk; a central shaft rotatable relative to the disk and disposed between the centrifugal weights, the central shaft comprising drive surfaces, wherein the disk is configured to be rotated by an input, wherein the central shaft is configured to rotate an output, wherein the centrifugal weights rotate between a disengaged position in which the centrifugal weights do not interface with drive surfaces and an engaged position in which the centrifugal weights interface with the drive surfaces, and wherein the centrifugal weights are disposed inside of a perimeter of the disk when the centrifugal weights are in the engaged position.

A full and enabling disclosure of the present invention, including the best mode of making and using the present systems and methods, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:.

Reference now will be made in detail to embodiments of the present invention, one or more examples of which are illustrated in the drawings. Moreover, each example is provided by way of explanation, rather than limitation of, the technology. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present technology without departing from the scope or spirit of the claimed technology. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents.

The singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. For example, a process, method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive- or and not to an exclusive- or.

Terms of approximation, such as "about," "generally," "approximately," or "substantially," include values within ten percent greater or less than the stated value. When used in the context of an angle or direction, such terms include within ten degrees greater or less than the stated angle or direction. For example, "generally vertical" includes directions within ten degrees of vertical in any direction, e.g., clockwise or counter-clockwise.

Benefits, other advantages, and solutions to problems are described below with regard to specific embodiments.

In general, clutch mechanisms and machines using clutch mechanisms described herein operate using centrifugal force to rotate centrifugal weights between a disengaged position and an engaged position. As a disk of the clutch mechanism begins to rotate, the centrifugal weights rotate from the disengaged position to the engaged position. In the engaged position, the centrifugal weights interface with one or more drive surfaces of a central shaft to transmit power from an input to an output, e.g., from an input gear interfaced with the clutch mechanism to an output gear interfaced with the clutch mechanism. In the disengaged position, the centrifugal weights are not interfaced with the drive surfaces and power is not transmitted from the input to the output. The centrifugal weights can start to rotate when the disk, upon which the centrifugal weights are coupled, reaches a threshold rotational speed. At and above the threshold rotational speed, the centripetal force of rotation can cause the centrifugal weights to move. At a threshold rotational speed, the centrifugal weights can interface with the drive surfaces of the central shaft to drive the central shaft. The central shaft is coupled to an output. Accordingly, driven rotation of the central shaft by the centrifugal weights can transmit power from the input to the output.

Referring now to the drawings, <FIG> illustrates a lawnmower <NUM> in accordance with an exemplary embodiment of the present disclosure. The lawnmower <NUM> generally includes a body <NUM>, a handle <NUM> extending from the body <NUM> to allow an operator to push or control the lawnmower <NUM>, a bagging unit <NUM> coupled with the body <NUM> and configured to collect debris and clippings ejected from a mowing area of the body <NUM> when the lawnmower <NUM> is in use, and a plurality of walking elements in the form of, e.g., wheels <NUM>. The lawnmower <NUM> further includes a battery storage area <NUM> configured to receive one or more batteries (not illustrated) and a prime mover, such as a motor <NUM> (<FIG>), which drives the wheels <NUM>. The lawnmower <NUM> can further include a deck height adjustment assembly <NUM> which allows the operator to control a height of cut. The deck height adjustment <NUM> may be adjustable through an interface located at the handle <NUM>. While the lawnmower <NUM> depicted in <FIG> is a walking mower (i.e., an operator walks behind the mower to control the mower), in one or more other embodiments, the lawnmower <NUM> can include a riding lawnmower or even another type of equipment, such as, e.g., a tractor, a snow thrower, an edger, or the like. While the following description relates to control of a driving aspect of the lawnmower <NUM>, i.e., the described embodiment transmits powers from the motor <NUM> to the wheels <NUM>, in other embodiments the described system can affect control of a different aspect of the machine, e.g., a selective power transmitter between a motor and a cutting blade, auger, or the like.

<FIG> illustrates a schematic view of an exemplary drive system <NUM> of the lawnmower <NUM> which transmits power from the motor <NUM> to opposite wheels 108a and 108b. The wheels 108a and 108b can be, for example, left and right rear wheels of the lawnmower <NUM>. The wheels 108a and 108b can be interfaced with an axle <NUM> through gears 120a and 120b. The gears 120a and 120b can interface with a wheel gear <NUM> of each one of the wheels 108a and 108b. Thus, as the axle <NUM> rotates, the wheels 108a and 108b can be driven by the gears 120a and 120b through the wheel gears <NUM>. In an embodiment, the gears 120a and 120b can be uni-directional gears, e.g., sprag gears, which enable the operator to overrun the lawnmower <NUM>. Overrun is a condition whereby the speed of the lawnmower <NUM> exceeds a drive speed propelled by the motor <NUM>. For instance, by way of non-limiting example, the motor <NUM> may be operating at <NUM> miles per hour. When the operator pushes the lawnmower <NUM> to increase speed past the operating speed of <NUM> miles per hour, the gears 120a and 120b can allow the lawnmower <NUM> to overrun whereby the operator can affect a higher operational speed. The uni-directional gearing may also enable the operator to turn the lawnmower <NUM> without requiring adjustment of the operating speed or any internal gearing.

The lawnmower <NUM> can further include a transmission <NUM> which converts power from an output <NUM> of the motor <NUM> to the axle <NUM>. The transmission <NUM> can include, for instance, an input <NUM> in communication with the output <NUM> of the motor <NUM> and an output <NUM> in communication with the axle <NUM>. A clutch mechanism <NUM> can be disposed between the input <NUM> and the output <NUM> for selectively transmitting power from the input <NUM> to the output <NUM>. In some instances, the clutch mechanism <NUM> can be directly coupled with the output <NUM> of the motor <NUM>. In such instances, the output <NUM> from the motor <NUM> can be referred to as the input.

When the motor <NUM> is operating at low speeds, i.e., below a low-speed threshold, the clutch mechanism <NUM> may be disengaged such that power from the motor <NUM> is not transmitted from the input <NUM> to the output <NUM>. As the motor <NUM> increases speed, the clutch mechanism <NUM> may engage at, or around, the low-speed threshold to transmit power from the input <NUM> to the output <NUM>. Power from the output <NUM> can then be transmitted to the wheels 108a and 108b through the axle <NUM> and gears 120a and 120b, respectively, to drive the wheels 108a and 108b.

<FIG> illustrate a specific embodiment of the clutch mechanism <NUM>. <FIG> illustrates the clutch mechanism <NUM> in the disengaged position whereby the clutch mechanism <NUM> does not transmit power from the input <NUM> to the output <NUM>. <FIG> illustrates the clutch mechanism <NUM> in the engaged position whereby the clutch mechanism <NUM> transmits power from the input <NUM> to the output <NUM>.

Referring to <FIG>, the clutch mechanism <NUM> generally includes a disk <NUM> having a major surface <NUM> and an outer perimeter <NUM>. A first post 140A extends from the disk <NUM> in a direction generally perpendicular to the major surface <NUM>. Similarly, a second post 140B extends from the disk <NUM> in a direction generally perpendicular to the major surface <NUM>. The first and second posts 140A and 140B can be disposed at generally opposite sides of a central opening (not illustrated) of the disk <NUM>. For instance, the first and second posts 140A and 140B can be spaced apart by <NUM>°, or approximately <NUM>° around the central opening of the disk <NUM>. Centrifugal weights 142A and 142B can be coupled to the posts 140A and 140B, respectively. The centrifugal weights (collectively referred to by numeral <NUM>) can be rotatable with respect to the posts (collectively referred to by numeral <NUM>). As depicted in <FIG>, the centrifugal weights <NUM> are each in the disengaged position. As the disk <NUM> begins to rotate, the centrifugal weights <NUM> can rotate about the posts <NUM> in a direction indicated by arrows A in <FIG>. As described in greater detail below, the centrifugal weights <NUM> can thus move to the engaged position whereby the clutch mechanism <NUM> can transmit power to the output <NUM>.

In an embodiment, the clutch mechanism <NUM> can be configured such that the centrifugal weights <NUM> rotate at least <NUM>° as measured between the disengaged and engaged positions, such as at least <NUM>° as measured between the disengaged and engaged positions, such as at least <NUM>° as measured between the disengaged and engaged positions, such as at least <NUM>° as measured between the disengaged and engaged positions, such as at least <NUM>° as measured between the disengaged and engaged positions, such as at least <NUM>° as measured between the disengaged and engaged positions, such as at least <NUM>° as measured between the disengaged and engaged positions, such as at least <NUM>° as measured between the disengaged and engaged positions. In a more particular embodiment, the clutch mechanism <NUM> can be configured such that the centrifugal weights <NUM> rotate at least <NUM>° as measured between the disengaged and engaged positions, such as at least <NUM>° as measured between the disengaged and engaged positions, such as at least <NUM>° as measured between the disengaged and engaged positions, such as at least <NUM>° as measured between the disengaged and engaged positions, such as at least <NUM>° as measured between the disengaged and engaged positions, such as at least <NUM>° as measured between the disengaged and engaged positions, such as at least <NUM>° as measured between the disengaged and engaged positions.

Referring still to <FIG>, the centrifugal weights <NUM> can share a common size. More particularly, the centrifugal weights <NUM> can have a common mass and a common moment of inertia. In this regard, the centrifugal weights <NUM> can rotate at the same, or approximately same, rotational speed of the disk <NUM>. This can prevent wobble of the disk <NUM> which might otherwise occur under eccentric loading conditions. In instances with more than two centrifugal weights <NUM>, it may be possible to vary one or more aspects of opposite pairs of centrifugal weights <NUM>, e.g., two centrifugal weights <NUM> can have a first same shape while another two centrifugal weights <NUM> disposed between the two centrifugal weights <NUM> can have a second shape different from the first shape.

The centrifugal weights <NUM> can each generally include a body <NUM> defining a first end <NUM> and a second end <NUM>. The first end <NUM> can include an engagement <NUM>. By way of example, the engagement <NUM> can be a dog or other interface configured to interface with a central shaft <NUM> of the clutch mechanism <NUM>. The second end <NUM> can include an engagement <NUM>. The engagement <NUM> can be a dog or other interface configured to interface with an outer surface <NUM> of the disk <NUM> as described in greater detail below.

The disk <NUM> can include stops <NUM> which support the centrifugal weights <NUM> when the centrifugal weights <NUM> are in the disengaged position as illustrated in <FIG>. In the illustrated embodiment, the stops <NUM> are blocks extending from the disk <NUM>. In other embodiments, the stops <NUM> can include, e.g., pins, screws, springs, soft bumpers (e.g., rubber bumpers), or the like. The bodies <NUM> of each centrifugal weight <NUM> can include a stop surface <NUM> which rests against the stop <NUM>. In one or more embodiments, at least one of the stops <NUM> can include a flat surface against which a flat stop surface <NUM> of the centrifugal weight <NUM> can be supported when the centrifugal weights <NUM> are in the disengaged position.

A central shaft <NUM> is disposed at a generally central location of the disk <NUM>. In a particular embodiment, the central saft <NUM> is coaxial with the disk <NUM>. The central shaft <NUM> can extend through the central opening (not illustrated) in the disk <NUM> such that a portion of the central shaft <NUM> is on a first side of the disk <NUM> and another portion of the central shaft <NUM> is on a second, opposite side of the disk <NUM>. The central shaft <NUM> can be rotatable with respect to the disk <NUM>. In a particular embodiment, the disk <NUM> may rotate about the central shaft <NUM>. In this regard, the central shaft <NUM> can form an axle upon which the disk <NUM> rotates.

The central shaft <NUM> can include one or more drive surfaces <NUM>. In the illustrated embodiment, the central shaft <NUM> includes two drive surfaces <NUM> disposed on protrusions <NUM> extending from the central shaft <NUM> in a generally radial direction. In an embodiment, the protrusions <NUM> can prevent the disk <NUM> from sliding off the central shaft <NUM>.

As previously described, the input <NUM> can receive driving power from the prime mover of the lawnmower <NUM>. In the depicted embodiment, the input <NUM> is an input gear. The input gear can be coupled to a shaft and rotatable about a central axis. The input gear is rotated, e.g., counterclockwise, to rotatably drive the clutch mechanism <NUM>, e.g., clockwise. The input gear can interface with the clutch mechanism <NUM> at an outer gear <NUM> of the disk <NUM>. The outer gear <NUM> can be disposed at, or adjacent, the outer perimeter <NUM> of the disk <NUM>. In an embodiment, the outer gear <NUM> can form at least a portion of the outer perimeter <NUM> of the disk <NUM>. For example, a top land <NUM> of each tooth <NUM> of the outer gear <NUM> can form the outer perimeter <NUM> of the disk <NUM>.

In some instances, the input <NUM> and disk <NUM> of the clutch mechanism <NUM> can be coplanar. That is, the input <NUM> and disk <NUM> can lie along a same plane. In other instances, the input <NUM> and disk <NUM> can lie along parallel offset planes. That is, the input <NUM> and disk <NUM> can be parallel with one another but lie along different planes. In yet other instances, the input <NUM> and disk <NUM> can lie along angularly offset planes. For instance, the input <NUM> and disk <NUM> can form a beveled gear interface angularly offset, e.g., by <NUM>°, from one another.

At low operational speeds, e.g., below a low-speed threshold, the clutch mechanism <NUM> can appear as shown in <FIG>. As the speed of the clutch mechanism <NUM> increases as a result of increased rotational speed of the disk <NUM>, the centrifugal weights <NUM> can rotate about posts <NUM> as shown by arrow A. In certain instances, the clutch mechanism <NUM> can rotate in a range of rotational speeds whereby the centrifugal weights <NUM> are not supported by the stops <NUM> but the centrifugal weights <NUM> are also not in the engaged position. This may be referred to as an intermediate period where the centrifugal weights <NUM> are moving from the disengaged position to the engaged position. As the speed of rotation increases to the low-speed threshold, the centrifugal weights <NUM> can move to the engaged position as shown in <FIG>.

<FIG> illustrates the clutch mechanism <NUM> with the centrifugal weights <NUM> in the engaged position whereby the clutch mechanism <NUM> can transmit power from the input <NUM> to the output <NUM>. As depicted, the engagement <NUM> of each centrifugal weight <NUM> is in contact with a respective drive surface <NUM> of the central shaft <NUM> when the centrifugal weights <NUM> are in the engaged position. Moreover, the engagements <NUM> of each centrifugal weight <NUM> are interfaced with the disk <NUM>, e.g., at an outer surface <NUM> of the clutch mechanism <NUM>, such that further rotation of the centrifugal weights <NUM> about the posts <NUM> is prevented. In this state, each of the centrifugal weights <NUM> is compressed between the outer surface <NUM> of the clutch mechanism <NUM> and the drive surface <NUM> of the central shaft <NUM> such that each centrifugal weight <NUM> acts like a fixed power transmission member for transmitting power from the input <NUM> to the central shaft <NUM>. Accordingly, the output <NUM> is rotatably driven by the clutch mechanism <NUM> in the engaged position as illustrated in <FIG>.

The outer surface <NUM> of the clutch mechanism <NUM> is intended to refer to a surface of the clutch mechanism <NUM> disposed radially outside of the centrifugal weights <NUM> that maintains the centrifugal weights <NUM> in the engaged position. As the centrifugal weights <NUM> move to the outer surface <NUM>, the engagement <NUM> can interface with the drive surface <NUM> of the central shaft <NUM>. Without the outer surface <NUM>, it is possible that the centrifugal weights <NUM> would continue to rotate about the posts <NUM> as caused, e.g., by resistance and inertia of the central shaft <NUM>. That is, the outer surface <NUM> prevents over-rotation of the centrifugal weights <NUM>.

In the illustrated embodiment, the outer surface <NUM> comprises a surface extending from the disk <NUM> in a direction perpendicular, or generally perpendicular, to the major surface <NUM> of the disk <NUM>. The surface can extend continuously around the disk <NUM> or include, e.g., a plurality of surfaces against which the centrifugal weights <NUM> can interface. In one or more nonillustrated embodiments, the outer surface <NUM> can include a post, a screw, a spring, a bumper (e.g., a rubber bumper), or the like. In some instances, the outer surface <NUM> can have a same, or similar, construction as the stop <NUM>, e.g., the outer surface <NUM> and stop <NUM> can be integral with the disk <NUM>. In other instances, the outer surface <NUM> and stop <NUM> can have different constructions, e.g., the stop <NUM> can include a discrete (separate) component coupled with the disk <NUM> and the outer surface <NUM> can be integral with the disk <NUM>.

In an embodiment, the centrifugal weights <NUM> can be disposed inside of the perimeter <NUM> (<FIG>) when the centrifugal weights <NUM> are in the disengaged and engaged positions. That is, the centrifugal weights <NUM> may remain within the perimeter <NUM> of the disk <NUM> at all times during operation. In a more particular embodiment, all elements of the clutch mechanism <NUM> can remain within the outer perimeter <NUM> of the disk <NUM> at all times during operation. In this regard, the clutch mechanism <NUM> can be utilized in transmissions <NUM> without consideration for moving parts (e.g., the centrifugal weights <NUM>) which might form a new outermost perimeter of the clutch mechanism <NUM> at certain operational speeds. That is, by maintaining all components of the clutch mechanism <NUM> within the same outer perimeter <NUM> at all times during operation, the clutch mechanism <NUM> can be treated more similarly to any other operating gears or elements of the transmission <NUM> without requiring special accommodation.

In an embodiment, the centrifugal weights <NUM> can each define a centerline CL. The centerlines CL of the centrifugal weights <NUM> can be angularly offset from one another by less than <NUM>°, as measured when the centrifugal weights are in the engaged position, such as less than <NUM>°, as measured when the centrifugal weights are in the engaged position, such as less than <NUM>°, as measured when the centrifugal weights are in the engaged position. In the depicted embodiment, the centerlines CL of the centrifugal weights <NUM> are angularly offset from one another by less than <NUM>°.

<FIG> illustrates a view of the clutch mechanism <NUM> with the centrifugal weights <NUM> in the engaged position similar to <FIG>, however, <FIG> depicts the clutch mechanism <NUM> after <NUM>° of rotation, caused by rotation of the input <NUM>. The centrifugal weights <NUM> can remain in the position illustrated in <FIG> and <FIG> as the clutch mechanism <NUM> rotates, and more particularly as the clutch mechanism <NUM> rotates above the low-speed threshold. As the clutch mechanism <NUM> decreases speed below the low-speed threshold, the centrifugal weights <NUM> can move towards the stops <NUM>. Under a certain rotational speed, the centrifugal weights <NUM> can return to rest against the stops <NUM> as depicted in <FIG>.

To return the centrifugal weights <NUM> to the disengaged position, the clutch mechanism can include one or more urging elements, e.g., springs <NUM>, which provide a force to the centrifugal weights <NUM> to return them to the disengaged position. In the depicted embodiment, the springs <NUM> have first ends <NUM> coupled to the centrifugal weights <NUM> and second ends <NUM> coupled to the disk <NUM>. In other instances, the springs <NUM> may be connected between the centrifugal weights <NUM> and another portion of the clutch mechanism <NUM>, such as the stops <NUM> or a separate spring attachment point. The springs <NUM> can be, e.g., coil springs which are selected to have a spring constant and size to affect disengagement of the centrifugal weights <NUM> at a desired low-speed threshold. For instance, springs <NUM> with lower spring constants may remain engaged at lower low-speed thresholds while springs <NUM> with higher spring constants may disengage at lower low-speed thresholds.

<FIG> illustrates a simplified cross-sectional view of the transmission <NUM> as seen along Line A-A in <FIG>. As depicted in <FIG>, the input <NUM> transmits power to the clutch mechanism <NUM> through the outer gear <NUM>. The disk <NUM> of the clutch mechanism <NUM> then transmits the power to the centrifugal weights <NUM> (depicted in the engaged position with outer surface <NUM>). The centrifugal weights <NUM> then transmit the power to the central shaft <NUM> (through the interface between the engagement <NUM> and drive surfaces <NUM>). The central shaft <NUM> then transmits the power to the output <NUM> through a meshing interface, e.g., a gear <NUM>. As depicted, the output <NUM> can be in a different plane than at least one of the input <NUM> and the clutch mechanism <NUM>.

<FIG> depict a transmission <NUM> in accordance with another embodiment of the present disclosure. In particular, <FIG> depicts a perspective view of the transmission <NUM>. <FIG> depicts a perspective view of the transmission <NUM> with a cover <NUM> of the transmission removed. <FIG> depicts a front view of the transmission <NUM> as seen in the disengaged position with the cover <NUM> removed. <FIG> depicts a front view of the transmission <NUM> as seen in the engaged position with the cover <NUM> removed. <FIG> depicts a front view of the transmission <NUM> with one of the centrifugal weights <NUM> removed. <FIG> depicts a rear view of the centrifugal weight 704a removed in <FIG>. <FIG> depicts a perspective view of a central shaft <NUM> and an engagement mechanism <NUM> including protrusions <NUM> with drive surfaces <NUM>.

Referring initially to <FIG>, the transmission <NUM> includes a disk <NUM> having a geared edge <NUM>. The transmission <NUM> defines a volume housing components of the transmission <NUM> between the disk <NUM> and the cover <NUM>.

As seen in <FIG>, the volume defined by the disk <NUM> and cover <NUM> can house centrifugal weights 704a and 704b. Similar to the centrifugal weights 142a and 142b, the centrifugal weights 704a and 704b can move between engaged and disengaged positions. The centrifugal weights 704a and 704b are movably coupled, e.g., rotatably coupled, to the disk <NUM> through first and second posts 718a and 718b, respectively. Retaining rings <NUM> can retain the centrifugal weights <NUM> and 704b on the first and second posts 718a and 718b. The retaining rings <NUM> can sit within grooves located in the first and second posts 718a and 718b and prevent the first and second centrifugal weights 704a and 704b from sliding off the first and second posts 718a and 718b.

Stops <NUM> can be disposed on the disk <NUM> to limit rotational movement of the first and second centrifugal weights 704a and 704b relative to the first and second posts 718a and 718b, respectively. The stops <NUM> can have any one or more similar characteristics as compared to stops <NUM>. For example, the stops <NUM> can support the centrifugal weights 704a and 704b when the centrifugal weights 704a and 704b are in the disengaged position as illustrated in <FIG>. In the illustrated embodiment, the stops <NUM> are blocks extending from the disk <NUM>. In other embodiments, the stops <NUM> can include, e.g., pins, screws, springs, soft bumpers (e.g., rubber bumpers), or the like. Each of the centrifugal weights 704a and 704b can include a stop surface <NUM> which rests against the stop <NUM>. In one or more embodiments, at least one of the stops <NUM> can include a flat surface against which a flat stop surface <NUM> of a respective one of the centrifugal weights 704a and 704b can be supported when the centrifugal weights 704a or 704b are in the disengaged position.

<FIG> depicts a front view of the transmission <NUM> in the disengaged state, i. , the centrifugal weights 704a and 704b are disengaged from the drive surfaces <NUM> of protrusions <NUM> of the engagement mechanism <NUM>. As the transmission <NUM> starts spinning in the direction A, the centrifugal weights 704a and 704b can rotate in direction B. Referring to <FIG>, at a critical rotational speed of the disk <NUM> in the direction A, the centrifugal weights 704a and 704b can engage with the drive surfaces <NUM> of the protrusions <NUM> of the engagement mechanism <NUM>. At a relatively same time, drive surfaces <NUM> of the centrifugal weights 704a and 704b can engage with surfaces <NUM> of the disk <NUM> to prevent further rotation of the centrifugal weights 704a and 704b and drive the disk <NUM>. At such time, the disk <NUM> can drive the engagement mechanism <NUM> in the direction C. Thus, input power can be transmitted through the transmission <NUM> when the centrifugal weights 704a and 704b are in the engaged positions, as depicted in <FIG>. Meanwhile, the engagement mechanism <NUM> can transmit power to the central shaft <NUM> to drive the aforementioned wheels.

<FIG> depicts a view of the transmission <NUM> with one of the centrifugal weights 704a removed. As depicted, the centrifugal weight 704a can be engaged with the disk <NUM> through a spring <NUM>. The spring <NUM> can be disposed within a cutout <NUM> (<FIG>) of the centrifugal weight 704a. The spring <NUM> can be, e.g., a torsion spring, and can bias the centrifugal weight 704a to the disengaged position. In an embodiment, the disk <NUM> can include a receiving area, e.g., a groove <NUM>, in which a portion of the spring <NUM>, e.g., a finger of the torsion spring <NUM>, can fit. When the retaining clip <NUM> is in place within a groove of the first post 718a, the spring <NUM> can be fit within the groove <NUM> and prevented from escaping. Thus, the spring <NUM> can remain fixed relative to the disk <NUM>.

<FIG> depicts a view of the engagement mechanism <NUM> coupled with the central shaft <NUM>. In accordance with an embodiment, the engagement mechanism <NUM> can include a central hub <NUM> from which the protrusions <NUM> extend. The protrusions <NUM> can form pockets <NUM> in which the centrifugal weights 704a and 704b (<FIG>). In an embodiment, the pockets <NUM> can have acute angles as viewed along an axis of the central shaft <NUM>. In certain instances, the pockets <NUM> (e.g., the drive surfaces <NUM>) can be shaped to have a close fit with the centrifugal weights 704a and 704b. Tips <NUM> of the protrusions <NUM> may be rounded to facilitate entrance of the centrifugal weights 704a and 704b into the pockets <NUM>.

Claim 1:
A transmission comprising:
an input (<NUM>) comprising an input gear;
an output (<NUM>);
a centrifugal clutch mechanism (<NUM>) that transfers energy from the input (<NUM>) to the output (<NUM>), the centrifugal clutch mechanism (<NUM>) comprising:
a disk (<NUM>) having an outer gear (<NUM>) that meshes with the input gear;
centrifugal weights (<NUM>) movably coupled to the disk (<NUM>); and
a central shaft (<NUM>) rotatable relative to the disk (<NUM>) and extending through the disk (<NUM>), the central shaft (<NUM>) comprising drive surfaces (<NUM>),
wherein the disk (<NUM>) is rotatably coupled to the input (<NUM>),
wherein the output (<NUM>) is rotatably coupled to the central shaft (<NUM>),
wherein the centrifugal weights (<NUM>) rotate between a disengaged position in which the centrifugal weights (<NUM>) do not interface with drive surfaces (<NUM>) and an engaged position in which the centrifugal weights (<NUM>) interface with the drive surfaces (<NUM>), and
wherein the centrifugal weights (<NUM>) are disposed inside of a perimeter (<NUM>) of the disk (<NUM>) when the centrifugal weights (<NUM>) are in the engaged position.