CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. provisional application number 62/127,863 filed on March 4, 2015, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

Example embodiments generally relate to hand held power equipment and, more particularly, relate to a guide bar improvements for a chainsaw.

BACKGROUND

Chainsaws are commonly used in both commercial and private settings to cut timber or perform other rigorous cutting operations. Because chainsaws are typically employed in outdoor environments, and the work they are employed to perform often inherently generates debris, chainsaws are typically relatively robust hand held machines. They can be powered by gasoline engines or electric motors (e.g., via batteries or wired connections) to turn a chain around a guide bar at relatively high speeds. The chain includes cutting teeth that engage lumber or another medium in order to cut the medium as the teeth are passed over a surface of the medium at high speed.

Given that the chainsaw may be employed to cut media of various sizes, the length of the guide bar can be different for different applications. However, in most situations, the guide bar is relatively long, and may actually be substantially longer than the main body of the chainsaw. The guide bar is typically made of steel, and thus, the guide bar can be a substantial contributor to the overall weight of the chainsaw.

Reducing the weight of the chainsaw can allow it to be more easily controlled and carried for long periods of time. However, weight is not the only concern or point of possible improvement in relation to guide bar design. As such, it may be desirable to explore a number of different guide bar design improvements that could be employed alone or together to improve overall chainsaw performance.

BRIEF SUMMARY OF SOME EXAMPLES

Some example embodiments may provide for a guide bar constructed with laminate cores that can be glued together to incorporate various improvements. In some cases, the core laminate construction may allow a ceramic roller to be included in a roller bearing assembly provided in a nose wheel of the guide bar. Thus, the bearing assembly may essentially be a hybrid bearing assembly. Other improvements may also be possible, and the improvements can be made completely independent of each other, or in combination with each other in any desirable configuration. Accordingly, the operability and utility of the chainsaw may be enhanced or otherwise facilitated.

In an example embodiment, a chainsaw that includes a power unit and a working assembly powered responsive to operation of the power unit is provided. The working assembly includes a guide bar around which a chain is rotatable. The guide bar includes first and second side plates, a sprocket wheel, first and second shims, and a bearing assembly. The first and second side plates face each other and extend away from a housing to a nose. The sprocket wheel is provided at the nose between the first and second side plates and is rotatable about a hub. The first and second shims are disposed between the first and second side plates, respectively, and corresponding ones of first and second sides of the sprocket wheel. The bearing assembly is disposed between the hub and the sprocket wheel and includes a plurality of roller elements made of a first material and at least one roller element made of a second material that is different than the first material.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) Having thus described some example embodiments in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

FIG. 1 illustrates a side view of a chainsaw according to an example embodiment;

FIG. 2 illustrates a perspective view of an axial end (e.g., a forward portion or nose) of the guide bar of FIG. 1 in accordance with an example embodiment;

FIG. 3 illustrates an exploded perspective view of the axial end of the guide bar from the same perspective shown in FIG. 2 in accordance with an example embodiment;

FIG. 4 illustrates an exploded perspective view of the axial end of the guide bar from the opposing perspective in accordance with an example embodiment; and

FIG. 5 illustrates a partially cutaway perspective side view of the axial end with portions of a side plate of the guide bar and shim removed to expose a roller bearing assembly in accordance with an example embodiment. DETAILED DESCRIPTION

Some example embodiments now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all example embodiments are shown. Indeed, the examples described and pictured herein should not be construed as being limiting as to the scope, applicability or configuration of the present disclosure. Rather, these example embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like reference numerals refer to like elements throughout. Furthermore, as used herein, the term "or" is to be interpreted as a logical operator that results in true whenever one or more of its operands are true. As used herein, operable coupling should be understood to relate to direct or indirect connection that, in either case, enables functional interconnection of components that are operably coupled to each other.

FIG. 1 illustrates side view of a chainsaw 100 according to an example embodiment. As shown in FIG. 1, the chainsaw 100 may include a housing 110 inside which a power unit or motor (not shown) is housed. In some embodiments, the power unit may be either an electric motor or an internal combustion engine. Furthermore, in some embodiments, the power unit may include more than one electric motor where one such electric motor powers the working assembly of the chainsaw 100 and the other electric motor of the power unit powers a pump that lubricates the working assembly or provides momentum for moving other working fluids within the chainsaw 100. The chainsaw 100 may further include a guide bar 120 that is attached to the housing 110 along one side thereof. A chain (not shown) may be driven around the guide bar 120 responsive to operation of the power unit in order to enable the chainsaw 100 to cut lumber or other materials. The guide bar 120 and the chain may form the working assembly of the chainsaw 100. As such, the power unit may be operably coupled to the working assembly to turn the chain around the guide bar 120.

The chainsaw 100 may include a front handle 130 and a rear handle 132. A chain brake and front hand guard 134 may be positioned forward of the front handle 130 to stop the movement of the chain 122 in the event of a kickback. In an example embodiment, the hand guard 134 may be tripped by rotating forward in response to contact with a portion of the arm (e.g., the hand/wrist) of the operator of the chainsaw 100. In some cases, the hand guard 134 may also be tripped in response to detection of inertial measurements indicative of a kickback.

The rear handle 132 may include a trigger 136 to facilitate operation of the power unit when the trigger 136 is actuated. In this regard, for example, when the trigger 136 is actuated (e.g., depressed), the rotating forces generated by the power unit may be coupled to the chain either directly (e.g., for electric motors) or indirectly (e.g., for gasoline engines). The term "trigger," as used herein, should be understood to represent any actuator that is capable of being operated by a hand or finger of the user. Thus, the trigger 136 may represent a button, switch, or other such component that can be actuated by a hand or portion thereof.

Some power units may employ a clutch to provide operable coupling of the power unit to a sprocket that turns the chain. In some cases (e.g., for a gasoline engine), if the trigger 136 is released, the engine may idle and application of power from the power unit to turn the chain may be stopped. In other cases (e.g., for electric motors), releasing the trigger 136 may secure operation of the power unit. The housing 110 may include a fuel tank for providing fuel to the power unit. The housing 110 may also include or at least partially define an oil reservoir, access to which may be provided to allow the operator to pour oil into the oil reservoir. The oil in the oil reservoir may be used to lubricate the chain as the chain is turned.

As can be appreciated from the description above, actuation of the trigger 136 may initiate movement of the chain around the guide bar 120. A clutch cover 150 may be provided to secure the guide bar 120 to the housing 110 and cover over the clutch and corresponding components that couple the power unit to the chain (e.g., the sprocket and clutch drum). As shown in FIG. 1, the clutch cover 150 may be attached to the body of the chainsaw 100 (e.g., the housing 110) via nuts 152 that may be attached to studs that pass through a portion of the guide bar 120. The guide bar 120 may also be secured with the tightening of the nuts 152, and a tightness of the chain can be adjusted based on movement of the guide bar 120 and subsequent tightening of the nuts 152 when the desired chain tightness is achieved. However, other mechanisms for attachment of the clutch cover 150 and/or the guide bar 120 may be provided in other embodiments including, for example, some tightening mechanisms that may combine to tighten the chain in connection with clamping the guide bar 120.

As mentioned above, the guide bar 120 can be an important contributor to the weight of the chainsaw 100. Thus, it may be desirable to provide various improvements to the guide bar 120 to improve the functionality and/or decrease the weight of the guide bar 120. Various example embodiments will now be described in reference to FIGS. 2-5, which illustrate some of these example embodiments.

In this regard, FIG. 2 illustrates a perspective view of an axial end (e.g., a forward portion or nose) of the guide bar 120 in accordance with an example embodiment. FIG. 3 illustrates an exploded perspective view of the axial end from the same perspective shown in FIG. 2, and FIG. 4 illustrates an exploded perspective view from the opposing perspective in accordance with an example embodiment. FIG. 5 illustrates a partially cutaway perspective side view of the axial end with portions of a side plate of the guide bar 120 and shim removed to expose a roller bearing assembly in accordance with an example embodiment.

Referring to FIGS. 2-5, it can be appreciated that the guide bar 120 may be formed from two laminate core sheets that lie in parallel planes along side each other. These laminate core sheets may be made from stainless steel or other sufficiently rigid and durable materials. The laminate core sheets may be referred to herein as a first side plate 200 and a second side plate 210, respectively. The first and second side plates 200 and 210 may generally be spaced apart from each other be at least a certain distance, which may be substantially consistent over the lengths of the first and second side plates 200 and 210. In some embodiments, a sprocket wheel 220 may be provided in the space between the first and second side plates 200 and 210. The sprocket wheel 220 may be rotatable to interface with the cutting chain as the cutting chain turns around the axial end of the guide bar 120. The sprocket wheel 220 may be supported by a bearing assembly 230 described in greater detail below.

In an example embodiment, a shim may be provided between the sprocket wheel 220 and each of the first and second side plates 200 and 210. As such, a first shim 240 may be provided between the first side plate 200 and the sprocket wheel 220, and a second shim 242 may be provided between the second side plate 210 and the sprocket wheel 220. Each of the first and second shims 240 and 242 may be a relatively thin (e.g., about .1mm) steel plate. The first and second shims 240 and 242 may perform a sealing function relative to lubrication of components provided in the bearing assembly 230. However, it should be appreciated that some embodiments may not include any shims. In cases where shims are included, the first and second shims 240 and 242 may be produced by an etching process.

Rivets 250 may be provided to fix the bearing assembly 230, sprocket wheel 220, first and second shims 240 and 242, and the first and second side plates 200 and 210 together. As such, receiving holes may be formed and aligned in each of these components and the rivets 250 may pass through the aligned receiving holes to hold the entire assembly together. Although six rivets are shown in the examples, any number of rivets 250 could be employed in various example embodiments.

As shown in FIG. 5, the bearing assembly 230 may include a hub 300 having a lubrication reservoir 310 (or lubricant reservoir) disposed at a center thereof. The lubrication reservoir 310 may hold a lubricant (e.g., oil or grease) that can be provided to rolling elements 320 of the bearing assembly 230 via one or more channels 330 that may extend from the lubrication reservoir 310 toward the rolling elements 320 of the bearing assembly 230. The channels 330 may generally extend radially outwardly between the lubrication reservoir 310 and the rolling elements 320.

The rolling elements 320 (also referred to as roller elements) may be stainless steel spheres that are arranged in an annular channel formed around the hub 300. In an example embodiment the sprocket wheel 220 may have a hollow center and the hub 300 may fit within the hollow center. The hub 300 is fixed by the rivets 250, but the sprocket wheel 220 is to move with the movement of the chain. Thus, the bearing assembly 230 provides an interface to permit the rotation of the sprocket wheel 220 about the hub 300. As such, the rolling elements 320 may be disposed in the space between the inner periphery of the sprocket wheel 220 and the outer periphery of the hub 300. The rolling elements 320 may form a roller bearing assembly that allows relative motion between the hub 300 and the sprocket wheel 220 while the chain is being rotated, and the rolling elements 320 may be lubricated by the lubricant from the lubrication reservoir 310 during this process.

In some embodiments, at least one of the shims (e.g., the first shim 240) may include a valve element 340 disposed proximate to the lubrication reservoir 310 to facilitate sealing of the lubricant between the shims and the sprocket wheel 220 (i.e., proximate to the hub 300 and the rolling elements 320 of the bearing assembly 230), but allow the lubricant to be inserted into the lubrication reservoir 310. Accordingly, while the sprocket wheel 220 rotates, the first and second shims 240 and 242 may be protected from damage, and the first and second shims 240 and 242 may also hold the rolling elements 320 in place.

In an example embodiment, rather than having every rolling element 320 of the bearing assembly 230 made of ball bearing steel (or another rigid metallic material), at least one of the elements of the bearing assembly 230 may be provided as a ceramic roller 325. In many bearing assemblies, around twenty to forty-one rolling elements 320 may be provided in the bearing assembly 230 dependent upon the size of the guide bar 120 (and therefore also the size of the nose and the sprocket wheel 220). However, more or less may be included in different sized bars, and some special bars may include as many as 120 rollers. As such, for example, the bearing assembly 230 may include at least one ceramic roller 325 and the remaining rolling elements 320 may all be made of stainless steel (or another rigid metallic material). Although FIGS. 3-5 show one ceramic roller 325, it should be appreciated that two, three or even more, may be employed in other embodiments. When multiple ceramic rollers are employed, each ceramic roller may be equidistantly spaced from a next ceramic roller on either side thereof.

The ceramic roller 325 may have a much higher hardness than the other rolling elements 320 of the bearing assembly 230. Bearing assemblies can often be very sensitive to contamination from dirt and other debris. Thus, it may be considered important to keep the bearing assembly 230 clean and free of contamination in order to improve the wear characteristics of the components, and to increase the useful life of the bearing assembly 230. However, especially in light of the harsh environment in which chainsaws often operate, it is possible that sand, dirt and/or the like (i.e., debris) may enter into the bearing assembly 230. Rather than allowing the debris to damage the rolling elements 320, the provision of the ceramic roller 325 may allow the debris to be crushed so that the other rolling elements 320 are protected. As such, the bearing assembly 230 may be considered to be a hybrid bearing assembly since it employs different types of rolling elements. By including the ceramic roller 325 in a hybrid bearing assembly, the life of the bearing assembly 230 may be increased as much as 30%.

Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although the foregoing descriptions and the associated drawings describe exemplary embodiments in the context of certain exemplary combinations of elements and/or functions, it should be appreciated that different combinations of elements and/or functions may be provided by alternative embodiments without departing from the scope of the appended claims. In this regard, for example, different combinations of elements and/or functions than those explicitly described above are also contemplated as may be set forth in some of the appended claims. In cases where advantages, benefits or solutions to problems are described herein, it should be appreciated that such advantages, benefits and/or solutions may be applicable to some example embodiments, but not necessarily all example embodiments. Thus, any advantages, benefits or solutions described herein should not be thought of as being critical, required or essential to all embodiments or to that which is claimed herein. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.