Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
CHAINSAW CHAIN DESIGN FOR MAINTAINING GRINDING LEVEL
Document Type and Number:
WIPO Patent Application WO/2016/139582
Kind Code:
A1
Abstract:
A cutting chain (200) for a chainsaw (100) may include a plurality of drive links (210) and a plurality of cutter links (240/500) operably coupled to respective ones of the drive links (210). At least one of the cutter links (240/500) may include a base portion (280), a cutting portion (270/510) extending away from the base portion (280), and a depth gauge portion (260/520). The cutting portion (270/510) may include a side plate (300) and a top plate (310), and may have a leading edge (540). The depth gauge portion (260/520) may also have a leading edge (525), and may be configured at a different elevation than the cutting portion (270/510) to define a cutting depth based on the different elevation. The height of both the cutting portion (270/510) and the depth gauge portion (260/520) decreases moving away from the leading edges (540,525) to maintain the cutting depth responsive to recession of the leading edges (540,525) of the cutting portion (270/510) and the depth gauge portion (260/520).

Inventors:
SARIUS NIKLAS (SE)
SUNDBERG HANS-ÅKE (SE)
MILLENBERG JOHAN (SE)
GUNÉR JONATAN (SE)
Application Number:
PCT/IB2016/051142
Publication Date:
September 09, 2016
Filing Date:
March 01, 2016
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
HUSQVARNA AB (SE)
International Classes:
B27B33/14
Foreign References:
US4785700A1988-11-22
FR2797409A12001-02-16
FR2500357A11982-08-27
Other References:
None
Download PDF:
Claims:
CLAIMS:

1. A cutting chain (200) for a chainsaw (100), the cutting chain (200) comprising:

a plurality of drive links (210); and

a plurality of cutter links (240/500) operably coupled to respective ones of the drive links (210),

wherein at least one of the cutter links (240/500) comprises:

a base portion (280);

a cutting portion (270/510) extending away from the base portion (280), the cutting portion (270/510) including a side plate (300) and a top plate (310), the cutting portion having a leading edge (540); and

a depth gauge portion (260/520) having a leading edge (525), the depth gauge portion (260/520) being configured at a different elevation than the cutting portion (270/510) to define a cutting depth based on the different elevation,

wherein a height of both the cutting portion (270/510) and the depth gauge portion (260/520) decreases moving away from the leading edge (540) of the cutting portion (270/510) and the leading edge (525) of the depth gauge portion (260/520), respectively, to maintain the cutting depth responsive to recession of the leading edge (540) of the cutting portion (270/510) and the leading edge (525) of the depth gauge portion (260/520).

2. The cutting chain (200) of claim 1, wherein a slope of a top surface (560) of the cutting portion (270/510) is less than a slope of a top surface (570) of the depth gauge portion (260/520).

3. The cutting chain (200) of claim 2, wherein the depth gauge portion (260/520) includes a protrusion (526) disposed at the leading edge (525) of the depth gauge portion (260/520).

4. The cutting chain (200) of claim 3, wherein the protrusion (526) protrudes forward in a direction of advance of the cutting chain (200) relative to a remainder of the at least one of the cutter links (240/500).

5. The cutting chain (200) of claim 4, wherein the depth gauge portion (260/520) includes a peak (528) projecting upward to form an angle, a forward portion of the angle including the leading edge (525) and a rearward portion of the angle including the top surface (570) of the depth gauge portion (260/520).

6. The cutting chain (200) of any preceding claim, wherein the depth gauge portion (260/520) and the cutting portion (270/510) are made of the same material.

7. A cutter link (240/500) of a cutting chain (200) for a chainsaw (100), the cutter link (240/500) comprising:

a base portion (280);

a cutting portion (270/510) extending away from the base portion (280), the cutting portion (270/510) including a side plate (300) and a top plate (310), the cutting portion having a leading edge (540); and

a depth gauge portion (260/520) having a leading edge (525), the depth gauge portion

(260/520) being configured at a different elevation than the cutting portion (270/510) to define a cutting depth based on the different elevation,

wherein a height of both the cutting portion (270/510) and the depth gauge portion (260/520) decreases moving away from the leading edge (540) of the cutting portion (270/510) and the leading edge (525) of the depth gauge portion (260/520), respectively, to maintain the cutting depth responsive to recession of the leading edge (540) of the cutting portion (270/510) and the leading edge (525) of the depth gauge portion (260/520).

8. The cutter link (240/500) of claim 7, wherein a slope of a top surface (560) of the cutting portion (270/510) is less than a slope of a top surface (570) of the depth gauge portion (260/520).

9. The cutter link (240/500) of claim 8, wherein the depth gauge portion

(260/520) includes a protrusion (526) disposed at the leading edge (525) of the depth gauge portion (260/520).

10. The cutter link (240/500) of claim 9, wherein the protrusion (526) protrudes forward in a direction of advance of the cutting chain (200) relative to a remainder of the at least one of the cutter links (240/500).

11. The cutter link (240/500) of claim 10, wherein the depth gauge portion (260/520) includes a peak (528) projecting upward to form an angle, a forward portion of the angle including the leading edge (525) and a rearward portion of the angle including the top surface (570) of the depth gauge portion (260/520).

12. The cutter link (240/500) of any of claims 7-11, wherein the depth gauge portion (260/520) and the cutting portion (270/510) are made of the same material.

Description:
CHAINSAW CHAIN DESIGN FOR MAINTAINING GRINDING LEVEL

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. provisional application number 62/128,186 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 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 not desired 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 depth gauge portion of the cutter link to wear also in a manner that keeps a consistent relationship between cutting portion and depth gauge portion, may make the cutter links have cutting efficiencies that are not changed drastically 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 is 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 may include a base portion, a cutting portion extending away from the base portion, and a depth gauge portion. The cutting portion may include a side plate and a top plate, and may have leading edges. The depth gauge portion may also have a leading edge, and may be configured at a different elevation than the cutting portion to define a cutting depth based on the different elevation. The height of both the cutting portion and the depth gauge portion decreases moving away from the leading edges to maintain the cutting depth responsive to recession of the leading edges of the cutting portion and the depth gauge 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 in accordance with an example embodiment; FIG. 4, which includes FIGS. 4A and 4B, illustrates a side view of a cutter link before and after wear to show how cutting depth can be effected; and

FIG. 5 illustrates a side view of a cutter link of an example embodiment where a retreat in the leading edge of both the cutting portion and the depth gauge is configured to maintain a consistent cutting depth.

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 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, but the retreat of the leading edges of the cutting portion 270 can alter the cutting depth. FIG. 4, which includes FIGS. 4A and 4B, illustrates this point. In this regard, FIG. 4A illustrates a typical cutter link 240 when relatively new. As shown in FIG. 4A, the gap 290 is defined between the trailing edge of the depth gauge portion 260 and the leading edges of the cutting portion 270. A cutting depth 400 is defined based on the difference in height between the leading edge of the top plate of the cutting portion 270 and the highest point of the depth gauge portion 260. The cutting depth 400 helps to provide a smooth run for the chain and efficient cutting.

As the chain is used, the leading edges of the cutting portion 270 tend to be worn and retreat, as shown in FIG. 4B. Accordingly, the size of the gap 290' in FIG. 4B is larger than the gap 290 of FIG. 4A. However, the depth gauge portion 260 is not typically as prominent as the cutting portion 270 and therefore wears less, and sometimes very little by interaction with the wood. Instead, the depth gauge portion 260 may likely only encounter wear when filing or other sharpening activities are undertaken for the chain. Since the height of the cutting portion 270 decreases moving from the leading edges of the cutting portion 270 to the trailing edges of the cutting portion 270, the cutting depth 400' of FIG. FIG. 4B is smaller than the cutting depth 400 of FIG. 4A. As the cutting depth decreases, cutting efficiency may also decrease.

Accordingly, to improve the ability to maintain the cutting depth over time, an example embodiment may be provided to maintain a relatively consistent grinding level as the cutting portion wears. FIG. 5 illustrates a profile of a cutter link 500 in accordance with an example embodiment. The cutter link 500 includes a cutting portion 510 similar to the cutting portion 270 described above. However, the cutter link also includes a more prominent depth gauge portion 520 that is configured to wear (albeit at a lower rate than the cutting portion 510). A leading edge 525 of the depth gauge portion 520 is shown to retreat or recede (as indicated by arrow 530 between solid and dashed line positions). Meanwhile a leading edge 540 of the cutting portion 510 also retreats (as indicated by arrow 545 between solid and dashed line positions. An initial cutting depth 550 is also shown along with a post recession cutting depth 550' after the retreat of the leading edges. As can be appreciated from FIG. 5, the difference between the initial cutting depth and the post recession cutting depth 550' is much smaller than would otherwise occur (i.e., as shown in FIG. 4) if the cutter link 500 was not modified as described herein. Of note, the slope of the cutting portion 510 is less than a slope of the depth gauge portion 520 to maintain roughly the same cutting depth 550 during the recession process because the depth gauge portion 520 recedes more slowly than the cutting portion 510.

Accordingly, for example, the depth gauge portion 520 is provided so that the leading edge 525 protrudes at least slightly forward (i.e., in the direction of advance of the chain) relative to the remainder of the cutter link 500. The protrusion 526 is prominent and promotes friction with the material being cut to facilitate abrasion of the leading edge 525 of the cutter link 500. The leading edge 525 also includes a relatively prominent peak 528 that projects upward and forms a relatively sharp angle. A forward portion of the angle may correspond to the leading edge 525 and a rearward portion of the angle may correspond to the top surface 570 of the depth gauge portion 520. The peak 528 also provides a prominent surface that promotes friction with the material being cut to facilitate abrasion of the leading edge 525 of the cutter link 500. The promotion of friction at the leading edge 525 by the structures provided (e.g., the protrusion 526 and the peak 528) will tend to cause the leading edge to retreat 525 in the direction of arrow 530.

As can be appreciated from FIG. 5, the protrusion 526 and the peak 528 may increase friction to facilitate abrasion and retreat of the leading edge 525. However, the amount of friction encountered will be less than that to which the leading edge 540 of the cutting portion 510 encounters. Thus, the leading edge 525 of the depth gauge portion 520 can be expected to retreat at a slower rate than the leading edge 540 of the cutting portion 510. Given the fact that a top surface 560 of the cutting portion 510 has a gentler slope than a top surface 570 of the depth gauge portion 520, the different rates of retreat will tend to provide balance that maintains the cutting depth relatively constant. In this regard, while the retreat of the leading edge 525 of the depth gauge portion 520 is slower, there is a sharper reduction in the height of the peak 528, which will tend to offset the more rapid retreat of the leading edge 540 of the cutting portion 510 at a slower rate of height reduction based on the gentler slope of the top surface 560 of the cutting portion 510.

Accordingly, in an example embodiment, both the depth gauge portion 520 and the cutting portion 510 may be made of the same material, but they may abrade at different rates based on the shapes of the surfaces presented for friction with the material to be cut. However, the shapes of the surfaces presented for friction are provided in a manner that tends to balance the reduction in elevation of the cutting surface and depth gauge over time.

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.