CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. provisional application number 62/128,136 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 cutting chain 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 and types, it should be appreciated that the design of the chain itself may have an impact on the effectiveness of the cutting operations. In particular, cutter edges of the chain may wear over time. This wear occurs based on the edges being grinded or abraded by the material that the chain is cutting. As the chain is worn, it is undesirable for the efficiency of the chain to be excessively impacted by the wearing process.

As such, it may be desirable to explore a number of different chain design improvements that could be employed alone or together with other design changes to improve overall chainsaw, and cutting chain, performance. In particular, it may be desirable to design the cutting chain to have more consistent cutting performance over the life of the chain.

BRIEF SUMMARY OF SOME EXAMPLES

Some example embodiments may provide for a chainsaw chain constructed with a modification to cutter links to improve cutting efficiency. The modification to the cutter links of the chain may improve cutting efficiency and minimize the energy required for executing the cutting procedure, and also minimize the effects of normal wear on cutting efficiency. The modification, which involves designing the cutter links to be reversible so that the chain can cut in either direction, may make the cutter links have cutting efficiencies that change less noticeably as the cutting chain wears over time. The cutter links may therefore have better stay sharp properties and a longer useful life. 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 cutting chain for a chainsaw may be provided. The cutting chain may include a plurality of drive links and a plurality of cutter links operably coupled to respective ones of the drive links. At least one of the cutter links (i.e., a dual direction cutter link) may include a base portion, a cutting portion extending away from the base portion, and first and second depth gauge portions. The cutting portion may include a side plate and a top plate. The first and second depth gauge portions extend away from the base portion in the same direction as the cutting portion, but are disposed on opposite sides of the cutting portion. 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 side view of a chainsaw guide bar employing a chain according to an example embodiment;

FIG. 3 illustrates a perspective side view of one cutter link; and

FIG. 4 illustrates a side view of a cutter link of an example embodiment where the cutter link is enabled to cut in either direction.

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.

In some embodiments, the guide bar 120 may be formed from two laminate core sheets that lie in parallel planes along side each other to define a channel around a periphery of the guide bar 120. The chain (or at least a portion of the chain) may ride in the channel, as the rest of the chain rides along the periphery of the guide bar 120 to engage media for cutting. FIG. 2 illustrates a typical chain 200 disposed on the guide bar 120. The chain 200 includes a plurality of center drive links 210 that each include a portion thereof that rides in the channel. Each center drive link 210 is attached to an adjacent pair of side links 220 by rivets 230 that extend perpendicular to the longitudinal length of the links. A rivet 230 is provided at the front portion of each center drive link 210 to attach the center drive link 210 to the rear portion of a preceding side links 220 and another rivet 230 is provided at the rear portion of each center drive link 210 to attach the center drive link 210 to the front portion of a subsequent side links 220. As such, each pair of side links 220 connects to opposing sides of the center drive links 210, and the connections are repeated in alternating fashion to complete a circular or endless chain.

For some pairs of side links 220 of the chain 200 one of the side links may be formed as a cutter link 240. Meanwhile, pairs of side links that do not include a cutter link 240 may be referred to as tie links 250. The cutter links 240 may be provided with two portions including a depth gauge portion 260 and a cutting portion 270. The cutting portion 270 may generally engage material that extends beyond the depth of the depth gauge portion 260 when the chain 200 is rotated. Meanwhile, the tie links 250 may not include cutting portions or depth gauge portions and may be provided to simply extend the length of the chain 200 while providing a space between portions of the chain 200 that will create friction during cutting operations. If every side link 210 was a cutter link 240, the friction on the chain 200 would be very high, and it would be difficult to provide sufficient power to turn the chain, and control of the chainsaw 100 could also become difficult. Additionally, if the cutter links 240 were merely allowed to engage large portions of the media to be cut without a restriction on the cutting depth for each cycle, the friction would be high and the run of the chain would be less smooth. Accordingly, the depth gauge portion 260 allows a limit to be placed on the cutting depth or amount of material to be cut with each pass of the cutter link 240.

As shown in FIG. 3, the cutter links 240 may have a base portion 280 from which both the cutting portion 270 and the depth gauge portion 260 extend. The rivets may be passed through holes in the base portion 280. The cutting portion 270 may extend away from the base portion 280 in the same direction that the depth gauge portion 260 extends away from the base portion 280. However, the depth gauge portion 260 may be at one end of the cutter link 240 and the cutting portion 270 may be at the other end, separated from each other by a gap 290. Of note, the gap 290 may grow in size over time, as the cutting portion 270 is worn or abraded away due to use.

The cutting portion 270 may include a side plate 300 that extends upward away from the base portion 280. Although the side plate 300 generally extends in a direction parallel to plane in which the base portion 280 lies, the side plate 300 does not necessarily also lie in the same plane. In some cases, the side plate 300 may have a curved shape to bend slightly out of the plane. Moreover, in some embodiments, the side plate 300 may bend out of the plane and then back toward the plane as it extends away from the base portion 280. Regardless, the distal end of the side plate 300 may be joined with a top plate 310. The top plate 310 may lie in a plane that is substantially perpendicular to the plane in which the base portion 280 lies.

The side plate 300 may have a leading edge 302 and an inside face 304. The side plate may also have an outside face that is opposite the inside face 304, and a trailing edge that is opposite the leading edge 302. The top plate 310 may have a leading edge 312 that extends substantially perpendicular to the direction of extension of the base 280 (and in some cases also the direction of extension of the leading edge 302 of the side plate 300). The top plate 310 may also have a bottom face 314 and a top face 316. The top face 316 may be opposite the bottom face 314 and, in some cases, the top and bottom faces 316 and 314 may be in parallel planes. However, in some cases, the top and bottom faces 316 and 314 may be angled slightly toward each other as they extend away from the side plate 300. The top plate 310 may also have a trailing edge disposed opposite the leading edge 312.

In an example embodiment, the cutter link 240 may be formed by stamping, grinding and combinations thereof with or without other techniques also being employed. In a typical situation, as mentioned above, the cutter link 240 begins to become warn at the leading edge 312 of the top plate 310 and at the leading edge 302 of the side plate. This wearing may cause what is effectively a retreat (e.g., movement to the left) of the leading edges of the cutting portion 270. This retreat or recession of the leading edges of the cutting portion 270 will tend to widen the size of the gap 290 between the depth gauge portion 260 and the cutting portion 270.

As mentioned above, the depth gauge portion 260 generally allows a limit to be placed on the cutting depth or amount of material to be cut with each pass of the cutter link 240. Thus, the depth gauge portion 260 can be important relative to maintaining smooth and efficient cutting of the chain. However, as the cutting portion 270 experiences leading edge recession, the sharpness of the cutting portion 270 may be reduced. Although the operator may attempt to grind the chain to increase sharpness, this process may be time consuming and/or difficult for novice chainsaw operators. Accordingly, it may be preferable to enable the chain to be quickly put back into service with a sharp cutting edge. To achieve this, an example embodiment may provide for cutter links that are reversible and can cut in either direction. Thus, a change can quickly be made in the field to access a return to good cutting efficiency and a sharp blade.

Although one might consider simply providing the cutting portion 270 to be bi- directional, cutting efficiency could be reduced without the depth gauge portion 260. Accordingly, the example of FIG. 4 duplicates depth gauge portions on opposing sides of the cutting portion. In this regard, FIG. 4 illustrates one structure for a reversible cutter link 400 in accordance with an example embodiment.

The reversible cutter link 400 of FIG. 4 has a base portion 410 and a cutting portion 420 that may each be similarly structured to the base portions and cutting portions described above. However, as shown in FIG. 4, rather than simply including one leading edge, the reversible cutter link 400 includes a first leading edge 422 on one side of the cutting portion 420 and a second leading edge 424 on the opposite side of the cutting portion 420. As can be appreciated from FIG. 4, when the chain is rotated in the direction of arrow 430, the first leading edge 422 may engage the media being cut and the second leading edge 424 may actually act as a trailing edge in this direction of rotation. Meanwhile, when the chain is rotated in the direction of arrow 440, the second leading edge 424 may engage the media being cut and the first leading edge 422 may actually act as the trailing edge in this direction of rotation.

The reversible cutter link 400 also includes a corresponding separate depth gauge portion for each direction of rotation. In this regard, the reversible cutter link 400 includes a first depth gauge portion 450 disposed on one side of the cutting portion 420 and a second depth gauge portion 460 disposed on the opposite side of the cutting portion 420. Thus, no matter which way the chain is turned, a corresponding depth gauge portion may be encountered before the cutting portion 420 encounters the media being cut. Accordingly, as the chain turns in the direction of arrow 430, the first leading edge 422 may encounter the media being cut after the first depth gauge portion 450 sets the proper cutting depth for a smoother cutting experience. Moreover, as the first leading edge 422 begins to recede (e.g., in the direction shown by arrow 440), if the operator decides that a sharper cutting edge is needed, the operator can simply reverse the chain on the guide bar so that the chain is now turned in the direction of arrow 440. The second leading edge 424 (which may be sharp) may then encounter the media being cut after the second depth gauge 460. Wear processes for this operation may cause recession of the second leading edge 424 in the direction of arrow 430 until the operator decides that the chain should be replaced.

Example embodiments may therefore include a cutting chain 200 for a chainsaw 100. The cutting chain 200 may include a plurality of drive links 210 and a plurality of cutter links 240 operably coupled to respective ones of the drive links 210. At least one of the cutter links 240 (i.e., the dual direction cutter link 400) may include a base portion 410, a cutting portion 420 extending away from the base portion 410, and first and second depth gauge portions 450 and 460. The cutting portion 420 may include a side plate 300 and a top plate 310. The first and second depth gauge portions 450 and 460 extend away from the base portion 410 in the same direction as the cutting portion 420, but are disposed on opposite sides of the cutting portion 420. In an example embodiment, the first depth gauge portion 450 faces a first leading edge 422 of the cutting portion 420 and encounters media prior to the first leading edge 422 responsive to movement of the cutting chain 200 in a first direction 430, and the second depth gauge portion 460 faces a second leading edge 424 of the cutting portion 420 and encounters media prior to the second leading edge 424 responsive to movement of the cutting chain 200 in a second direction 440 that is opposite the first direction 430. In some cases, a first gap 480 separates the first depth gauge portion 450 from the first leading edge 422, and a second gap 490 separates the second depth gauge portion 460 from the second leading edge 424. In an example embodiment, any or all of the modifications described above may be employed, and the at least one of the cutter links 240 may be substantially symmetric about a centerline 495 of the at least one of the cutter links 240. In some cases, any or all of the modifications described above may be employed, and the at least one of the cutter links 240 may include the cutting portion 420 disposed on a first side of the drive links 210, and a next cutter link after the at least one of the cutter links 240 may include a cutting portion disposed on a second side of the drive links 210. The second side may be opposite the first side. In an example embodiment, any or all of the modifications described above may be employed, and the cutting chain 200 may be reversible on the chainsaw 100 to enable cutting regardless of a direction of orientation of the cutting chain 200 on the chainsaw 100.

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.