CN213859706U - High efficiency saw chain, and system and power saw including the same - Google Patents

Abstract

A high efficiency saw chain for a saw includes cutting links and drive links that are selected based on a ratio of components of the chain, such as a ratio of a height of a cutting tooth to a pitch of the chain, for a particular power range to provide a high efficiency saw chain. The present application further provides a system and power saw including the above-described high efficiency saw chain.

Description

High efficiency saw chain, and system and power saw including the same

RELATED APPLICATIONS

This application claims priority to U.S. patent application No.15/975,343 filed on 9.5.2018, and which is a continuation-in-part of this U.S. patent application No.15/975,343, and U.S. patent application No.15/975,343 claims priority to U.S. provisional application No.62/503,819 filed on 9.5.2017, the entire contents of which are incorporated herein by reference.

Technical Field

The present disclosure relates to the field of saw chains, and in particular to high efficiency saw chains.

Background

A chain saw generally comprises: a housing that houses a driving device (e.g., an engine); a guide rod extending from the housing; and an endless saw chain driven by the drive means and arranged to articulate about a periphery of the guide bar. Saw chains typically include various interconnected links, such as cutter links, drive links, and links. The cutter tooth links may be provided with a depth gauge located in front of and slightly below the subsequent cutting edge to substantially prevent the cutter tooth from over biting or penetrating into the wood.

SUMMERY OF THE UTILITY MODEL

In one aspect of the present invention, a high efficiency saw chain is provided, including a cutting link and a drive link. The cutting link includes: front cutting link rivet holes; post-cutting a chain link rivet hole; an upper cutting edge disposed at a first height relative to a line: the line is collinear with a lowermost portion of the cutting link and parallel to a line bisecting the front and rear cutting link rivet holes; a depth gauge opposite the cutting edge, the depth gauge having an upper surface disposed at a second height, the second height being substantially at or below the first height; and a gullet formed between the cutting edge and the depth gauge. The drive link includes: a front drive link rivet hole; and a rear drive link rivet hole to which the drive link is coupled via rivets that engage the front and rear drive link rivet holes, a chain pitch being defined as half a distance between a center of the front drive link rivet hole and a center of the rear drive link rivet hole. Selecting a ratio between the first height and the chain pitch for a particular power range to provide a high efficiency saw chain, wherein the ratio between the first height and the chain pitch is between about 1.22 and about 1.28.

In the above high efficiency saw chain, the first height is between about 0.400 inches and about 0.412 inches.

In the above high efficiency saw chain, the chain pitch is between about 0.315 inches and about 0.335 inches.

In the above high efficiency saw chain, the specific power range is 1 horsepower to 3 horsepower.

In the above high efficiency saw chain, the upper cutting edge is arranged at a third height with respect to the line bisecting the front and rear cutting link rivet holes, wherein a ratio between the third height and the chain pitch is between about 0.86 and about 0.92.

In the above high efficiency saw chain, the third height is between about 0.285 inches and about 0.295 inches.

In the above high efficiency saw chain, a ratio between the first height and the second height is selected to provide a high efficiency saw chain, wherein the ratio between the first height and the second height is between about 1.05 and about 1.10.

In another aspect of the present invention, a system is provided that includes the above-described high efficiency saw chain and a drive sprocket configured to drive the high efficiency saw chain.

The system may further include a guide bar configured to guide the high efficiency saw chain.

In yet another aspect of the present invention, a power saw is provided, which includes the above-mentioned high efficiency saw chain.

The power saw may further include a drive sprocket configured to drive the high efficiency saw chain.

The power saw may further include a guide bar configured to guide the high efficiency saw chain.

Drawings

The embodiments will be readily understood by the following detailed description in conjunction with the accompanying drawings. Embodiments are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings.

Fig. 1 illustrates a side view of a high efficiency cutting chain in accordance with various embodiments.

Fig. 2 illustrates a side view of a drive sprocket for a high efficiency cutting chain in accordance with various embodiments.

Fig. 3 illustrates a side view of a high efficiency cutting chain, in accordance with various embodiments.

Fig. 4 illustrates a side view of a high efficiency cutting chain, in accordance with various embodiments.

Fig. 5 is a graph of cutting efficiency versus chain pitch showing the unexpectedly superior performance of the disclosed high efficiency cutting chain relative to prior cutting chain designs.

FIG. 6 is a graph of chain cutting tooth height to chain pitch ratio versus cutting efficiency, which demonstrates the unexpectedly superior performance of the disclosed high efficiency cutting chain relative to prior cutting chain designs.

Detailed Description

In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration embodiments which may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of embodiments is defined by the appended claims and their equivalents.

Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding the embodiments; however, the order of description should not be construed as to imply that these operations are order dependent.

The description may use perspective-based descriptions such as up/down, back/front, and top/bottom. These descriptions are merely used to facilitate the discussion and are not intended to limit the application of the disclosed embodiments.

The terms "coupled" and "connected," along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. Rather, in particular embodiments, "connected" may be used to indicate that two or more elements are in direct physical contact with each other. "coupled" may mean that two or more elements are in direct physical contact. However, "coupled" may also mean that two or more elements are not in direct contact with each other, but yet still cooperate or interact with each other.

For the purposes of this description, phrases in the form "a/B" or in the form "a and/or B" mean (a), (B), or (a and B). For purposes of description, a phrase in the form of "at least one of A, B and C" means (a), (B), (C), (a and B), (a and C), (B and C), or (A, B and C). For the purposes of this description, a phrase in the form "(a) B" means (B) or (AB), i.e., a is an optional element.

The specification may use the term "embodiment" or "embodiments," which may each refer to one or more of the same or different embodiments. Furthermore, the terms "comprising," "including," "having," and the like, as used with respect to embodiments, are synonymous.

Embodiments disclosed herein provide an improved high efficiency saw chain for use in low power chainsaw operations, such as hand-held power chainsaws. Through careful design and experimentation, the present inventors have selected various parameters of the saw chain to provide a chain with high cutting efficiency relative to existing cutting chain designs (see, e.g., fig. 5). This results in the following saw chain: the saw chain requires less energy and/or power to achieve the same cut as a conventional typical saw chain.

The parameters (also referred to as factors) may be manipulated in designing the saw chain and may be used to adjust power consumption or cutting efficiency. Many factors affect both power consumption and efficiency. Typically, in a completely new design, a target power consumption value is set, as well as some other system variables, such as system weight, required feed load, system RPM, and other factors related to the cutting system as a whole. The target power level affects the first factor decision, which is the pitch selected for the chain. Pitch and power are positively correlated because a larger pitch results in a higher power level being required and a smaller pitch results in a lower power level being required. Once the pitch is selected, the remaining chain factors are adjusted to provide an appropriate ratio between many of the chain and bar system interrelationships. These factors may include cutter height and cutter length, drive link pitch to cutter pitch ratio, material thickness, cutter kerf width, and bar-to-kerf clearance. In an embodiment, the cutting kerf width is selected to be between about 0.200 inches and about 0.230 inches. In an embodiment, the rod to slit gap is selected to be between about 0.060 inches and about 0.100 inches. Additional cutting tooth design elements that affect a particular cutting pattern include depth gage, cutting corner radius, fixed cutting angle, and filed cutting angle. As a result of the need to keep the factors and factor ratios close to their optimum values, typical chain designs have evolved into relatively narrow design spaces that create substantial visual similarity between the designs. However, the effect of many factors on cutting system efficiency or some other performance metric is not linear. The present inventors have unexpectedly discovered unexpectedly high efficiency regions through careful manipulation of these design factors.

One ratio of non-linearity is the feed load/depth gauge ratio. As disclosed herein, high efficiency saw chains have been developed in which the entire chain is designed in the following window of ratios: the most influential size and ratio is allowed to approach its optimum while placing the feed load/depth gauge ratio and the ratio of depth of cut to the maximum of depth of cut at its optimum point. The proportional size targets the optimum efficiency and the correct area above the inflection point in the feed load/depth gauge relationship when the feed load and power range are simultaneously held at fixed values. This design space provides the following performance characteristics: the performance characteristics cannot be inferred from linear scaling or a given response value, such as power or efficiency, cannot be changed by modifying a dimension on an existing design.

As shown in fig. 5 and 6, the selection of various factors produces a much larger saw chain (high efficiency saw chain) than would be expected for a comparable pitch chain (325 standard). The graph shown in fig. 5 illustrates the relationship between the pitch and the cutting efficiency. Linearly guessing from 1/4 pitch to 3/8 pitch would not predict the efficiency of the disclosed high efficiency cutting chain. Even with the deviation between the standard 3/8 and 3/8 low profiles, the cutting efficiency of the present high efficiency cutting chain will still not be predicted.

The graph shown in fig. 6 illustrates the relationship between the ratio of the tooth height to the pitch and the cutting efficiency. As shown in fig. 6, standard 3/8 chain, standard 1/4 chain, standard.325 chain, and even 3/8 low profile chain illustrate a linear relationship between cutting efficiency and cutter height pitch ratio. However, the disclosed high efficiency chains exhibit an unexpectedly superior increase in efficiency. This cutting efficiency stems from the design of the disclosed high efficiency cutting chain for a particular application (power range and feed load) rather than a generic chain intended for several applications. In an embodiment, a high efficiency chain as defined herein may operate in a power level range of 1-3 horsepower, with a 5-8 pound feed load applied by the user at 2 horsepower.

In an embodiment, the ratio of the feed load to the depth gauge set amount for the high efficiency saw chain is between about 330 and about 380. This compares favorably with a ratio of feed load to depth set for conventional saw chains of between about 250 and about 310. In an embodiment, the depth gauge for the high efficiency saw chain is set between about 0.015 inches and about 0.020 inches. This compares favorably with depth gauges of between about 0.020 and about 0.030 for conventional saw chains.

In various embodiments, the chainsaw may include a guide bar extending from a body of the chainsaw. The body may comprise a housing, wherein a motor is arranged within the housing to drive the saw chain around the guide bar. The guide bar may comprise a pair of tracks with a groove arranged between the tracks. The guide bar may include one or more sprockets at ends of the guide bar with an elongated portion (e.g., a straight portion or a portion with a slight curvature) disposed between the ends of the guide bar. For example, the guide bar may include a drive sprocket at a proximal end of the guide bar and/or a nose sprocket at a distal end of the guide bar.

In various embodiments, the saw chain may include a plurality of links coupled to one another, including one or more cutting links, drive links, and/or tabs. The links may include a pair of rivet holes (e.g., a front rivet hole and a rear rivet hole) to couple the links to respective adjacent links. The drive link may be a center link that rides in a groove of the guide bar and/or engages a pocket of the sprocket. The tab may be a side link (e.g., a left side link or a right side link) that engages one of the rails of the guide bar. The tie straps may couple successive drive links to one another (e.g., with rivets disposed through rivet holes of the tie straps and/or rivet holes of the drive links, or via another device/coupling).

The disclosed high efficiency cutting chain may include cutter teeth/links, lugs, and drive links. The cutting link of the saw chain includes front and rear cutting link rivet holes and an upper cutting edge disposed at a first height relative to a line collinear with a lowermost portion of the cutting tooth and parallel with a longitudinal centerline bisecting a center of the rivet hole. In an embodiment, the first height is between about 0.400 inches and about 0.412 inches. The cutting links may include cutting edges and depth gauges separated by tooth slots. The depth gauge may have an upper surface and the following rear face: the back face generally faces the tooth slot and is opposite the cutting edge. The depth gauge has an upper surface disposed at a second height, relative to a line collinear with the lowermost portion of the cutting tooth, that is substantially at or below the first height, i.e., the height of the upper cutting edge. In an embodiment, the ratio between the first height and the second height is selected to provide a high efficiency saw chain. The ratio of the cutting tooth height above a line collinear with the lowest part of the cutting tooth to the depth gauge height is used to control cutting performance, safety and vibration. In an embodiment, the ratio between the first height and the second height selected to provide a high efficiency saw chain is between about 1.05 and about 1.10.

The tooth cutting height may also be determined relative to a longitudinal centerline disposed through the middle of adjacent rivet holes. The distance between the cutter tooth height and the longitudinal centerline may be referred to as a third height.

The cutter link may be coupled with the drive link using, for example, rivets that pass through front cutting link rivet holes and rear drive link rivet holes. The drive link may include front and rear drive link rivet holes, the drive link being coupled to the cutting link via rivets engaged with the front and rear cutting link rivet holes and rivets engaged with the rear and front drive link rivet holes of the aft drive link.

Typically, the chain pitch is the distance between three consecutive rivets divided by two. The ratio of pitch to tooth cutting height is determined by the specific power range. For the disclosed high efficiency cutting chain, the chain pitch may be defined as half the distance between the center of the front drive link rivet hole and the center of the rear cutting link rivet hole. In an embodiment, the ratio between the first height and the chain pitch is selected for a specific power range to provide a high efficiency cutting chain. In an embodiment, the ratio between the first height and the chain pitch is between about 1.22 and about 1.28. In an embodiment, the chain pitch is between about 0.315 inches and about 0.335 inches. In other embodiments, the ratio between the third height and the pitch is between about 0.86 and about 0.92, wherein the third height is between about 0.285 inches and about 0.295 inches.

In an embodiment, the cross-sectional area of the cutter links and tabs around the rivet are sized to provide a tensile strength and a safety factor based on the power range for which they are designed. Lower power chains require less material to provide the required strength. In an embodiment, the cross-sectional area below the centerline of the rivet hole is greater than the area above the centerline for the footprint of the chain. This allows for wastage of cutter teeth and chassis footprint during use while still maintaining adequate tensile strength and safety. Further, in certain embodiments, the height of the cutter links to the top of the lug is sized to provide an open area for proper chip evacuation.

The cutting link pitch is defined as the distance between the center of the front cutting link rivet hole and the center of the back cutting link rivet hole. The gear cutting drive pitch is defined as the distance between the center of the front drive link rivet hole and the center of the rear drive link rivet hole. In an embodiment, the ratio of the cutter link pitch to the drive link pitch is selected to provide a high efficiency saw chain. In an embodiment, the ratio of the cutter link pitch to the drive link pitch is between about 1.15 and about 1.19. In an embodiment, the cutter link pitch is between about 0.345 and about 0.355. In an embodiment, the drive link pitch is between about 0.288 and about 0.308.

The gauge of a saw chain is typically measured by the thickness of the drive links. In certain embodiments, the disclosed saw chain has been designed to provide the following chain specifications: the chain gauge is not as thick as a typical chain without sacrificing chain strength. This, in combination with other features, may provide a saw chain with improved efficiency. In an embodiment, the disclosed saw chain has been designed to provide a chain gauge width of between about 0.040 and about 0.046.

In certain embodiments, the cutting teeth of the saw chain are optimized to provide an increase in cutting efficiency and thus an increase in efficiency of the saw chain. For example, efficiency may be improved in various embodiments (i.e., those embodiments having a positive difference between the sharpening width and the opening width). These geometric constraints may provide performance improvements for any suitable form of shrouded cutter link. Examples of suitable cutting teeth may be found in U.S. patent No.9,610,702, which is incorporated herein by reference in its entirety.

Embodiments disclosed herein may improve cutting performance without sacrificing the life expectancy of the cutter links. This life is generally determined by the number of sharpenings (e.g. sharpening with a round pencil file) that the cutter links can withstand before the sharpening surface recedes too far for the cutter links to be used. Generally, the thickness of the sharpening surface is increased to nominally extend the life of the cutter links without regard to the relative geometry of the cutter links (and the attendant impact on cutting performance). These geometries may enable the cutter links to maintain the following "thick" sharpened surfaces: this "thick" sharpened surface can withstand repeated sharpening while achieving some or all of the performance improvements described herein. Performance advantages can be seen for cutter links of any suitable size with a sharpening width greater than the width of the opening.

Embodiments of chainsaw cutting tooth links and related apparatus and methods are disclosed herein. The cutter links described herein may improve chainsaw cutting performance by cutting through a desired media (e.g., wood) more quickly and smoothly than conventional cutter links. In particular, the cutter links herein may improve the cutting efficiency of the chainsaw, which is a measure that quantifies the ability of the saw chain to convert the power provided by the saw into cutting speed and material removal.

In some embodiments, a high efficiency saw chain includes a snubber drive link. In an embodiment, the bumper drive link has a rearwardly extending tail guard or bumper portion of the drive link. The bumper portion of the drive link may be positioned alongside the depth gauge of the following cutting link: the cutting links share a common pivotal connection with the drive links. Double thickness depth gauges and tails can be formed and can more effectively resist penetration into the wood fibers at the bottom of the cut (as compared to an elongated single thickness) and can significantly increase resistance to excessive penetration of subsequent cutting links. The articulation between the snubber drive link and the subsequent cutter link effectively creates an elongation of the depth gauge (e.g., as a combination of the cutter link depth gauge and the snubber portion of the snubber drive link) as the chain traverses the nose portion of the chainsaw bar. The extended composition depth gauge provides stability to the chain and, as discussed briefly above, also helps prevent the cutting surface from biting into or penetrating too deeply into the uncut wood. These functions may help to reduce possible kickback.

In various embodiments, the bumper portion of the bumper drive link provides additional resistance to penetration of wood fibers while minimizing negative impact on cutting performance by minimizing the portion of the bumper drive link that extends into the gullet of the cutting link, or in other words, helping to maximize the gullet opening for enhanced chip flow. In various embodiments, the configurations of the leading and trailing portions of the bumper drive link may be cooperatively formed such that the slope of the leading portion tilts the wood being cut in a direction that projects above the leading edge of the trailing portion, which itself is shaped to avoid having corners that may dig into the cutout, while the trailing portion may be formed to provide an extended edge along the top of the trailing portion. In various embodiments, the drive links may also be released in a central region forward of the tail portion of the center link to provide additional chip carrying capacity.

A system is disclosed that includes a high efficiency saw chain and a drive sprocket configured to drive the high efficiency saw chain. In an embodiment, the system further comprises a guide bar configured to guide the high efficiency saw chain.

A power saw including a high efficiency saw chain is disclosed. In an embodiment, the power saw further comprises a drive sprocket configured to drive the high efficiency saw chain. In an embodiment, the power saw further comprises a guide bar configured to guide the high efficiency saw chain.

Fig. 1 illustrates a high efficiency cutting chain 10 according to various embodiments. The high efficiency cutting chain 10 also includes cutter links 30, links 40, and drive links 50. The cutter links 30 of the saw chain 10 include cutting edges 32 and depth gauges 34 separated by gullets 36. The depth gauge 34 may have an upper surface and a rear surface that generally faces the gullet 36. The cutter link 30 may be coupled with the drive link 50 with, for example, a rivet passing through the rivet hole 38.

A longitudinal lower line 70 is shown in fig. 1 collinear with the lowest portion of the cutting tooth. The longitudinal centerline 60 may be disposed through the middle of the adjacent rivet holes 38.

A line 63 parallel to the longitudinal centerline 60 and parallel to the lower line 70 may be disposed at the top corner 33 of the cutting surface 32 of the cutter tooth 30. The distance between the lower line 70 and the parallel line 63 may be used to define the cutting tooth height 61, which cutting tooth height 61 is referred to above as the first height. The distance between the centerline 60 and the parallel line 63 may be used to define a cutting tooth height 66, which cutting tooth height 66 is referred to above as a third height. The tooth height has been selected to provide a high efficiency cutting chain 10.

In an embodiment, the cross-sectional area below the centerline 60 is greater for the chain footprint than for the area above the centerline. This allows for the wearing out of the cutter teeth and the footprint of the chassis during use while still maintaining adequate tensile strength and safety. Further, in certain embodiments, the height of the cutting teeth from the line 66 to the top of the web is sized to provide an open area for proper chip evacuation. A second set of centerlines 67 and 68 perpendicular to the longitudinal first centerline 60 may be disposed through the rivet hole 38 and used to define a distance 69 between the three rivets. The pitch of the chain is the distance between three consecutive rivets divided by two. Thus, the pitch is distance 69 divided by two. In an embodiment, the ratio between the tooth height and pitch has been selected to provide a high efficiency cutting chain 10 for a particular power range. In an embodiment, the ratio between the height and the depth gauge set amount has been selected to provide a high efficiency saw chain. The ratio of pitch to tooth cutting height is determined by the specific power range. Cutting performance, safety and vibration are controlled by the ratio of the height of the cutting tooth to the height of the depth gauge above the rivet centerline.

Fig. 2 illustrates a drive sprocket 200 that mates with the chain of fig. 1. In an embodiment, the tooth spaces 201 of sprocket 200 match the pitch distance of cutting chain 10 of fig. 1.

Fig. 3 and 4 illustrate a high efficiency cutting chain 10 including a snubber drive link 20 according to various embodiments. The high efficiency cutting chain 10 includes cutter links 30, links 40, and in some embodiments, non-snubber drive links 50. The cutter links 30 of the saw chain 10 include cutting edges 32 and depth gauges 34 separated by gullets 36. The depth gauge 34 may have an upper surface and a rear surface that generally faces the gullet 36. The cutter link 30 may be coupled with the damper drive link 20 with, for example, rivets that pass through rivet holes 38. The damper drive link 20 includes a body portion 21 and a damper portion 22, the damper portion 22 extending or protruding both radially upward and rearward from the center of the body portion 21 of the damper drive link 20. The bumper portion 22 may reduce backlash by extending slightly radially as the bumper portion 22 traverses the nose of the chainsaw bar (see fig. 4). Additionally, the bumper portion 22 may increase the following surface area of the bumper drive link 20: this surface area may participate in the recoil movement, thereby reducing the recoil energy. In addition, the length and shape of the bumper portion 22 may be modified to facilitate cutting performance.

Fig. 3 shows a side view of the saw chain 10 showing the cutting link 30 and the bumper drive link 20 and illustrating the respective first positions 12 of the saw chain 10 according to various embodiments. Fig. 4 shows a side view of the saw chain 10, the cutting link 30 and the bumper drive link 20 illustrating the respective second position 14 of the saw chain 10 according to various embodiments. The cutter link 30 and the snubber drive link 20 may be in the first position 12 when traveling over a substantially linear stroke of the rod track of the rod, and may be in the second position 14 when traveling circumferentially around the nose of the rod. In some embodiments, the height of the top edge 23 of the bumper portion 22 can be less than the height of the upper surface of the depth gauge 34 when these components are traveling on the linear travel of the upper and lower bar tracks of the guide bar. In some examples, the height of the top edge 23 of the bumper portion 22 may be low enough so that the bumper drive link is actually a conventional drive link. In some examples, the height of the top edge 23 of the bumper portion 22 may be as high as the depth gauge. In certain examples, the top edge 23 of the bumper portion 22 has a height of between about 0.005 inches above the depth gauge and about 0.030 inches below the depth gauge.

In various embodiments, the damper drive link 20 may include the following damper portions 22: the bumper portion 22 is adapted to extend partially into the upper region of the gullet 36. The bumper portion 22 may have a top edge 25, and in some embodiments, the top edge 25 may be below the upper surface of the depth gauge 34 when in the first position 12. The bumper drive link 20 may have a recess 27 on a trailing edge 26 with a top portion 28, and the bumper drive link 20 may include a forwardmost portion 24, the forwardmost portion 24 being disposed below and forward of the tip 25 of the bumper portion 22. In an embodiment, when the chain 10 is in the first position 12 with its straight portion traversing the rod, the distance between the longitudinal first centerline 60 and the tip 25 is greater than the distance between the longitudinal first centerline 60 and the top portion 28 of the trailing edge 26. In various embodiments, the recesses 27 are sized to reduce the amount of drive link material protruding into the gullets 36 of the cutter link, which in turn reduces the impact on the flow of swarf through the gullets 36, thereby promoting better cutting performance. A second line 63 parallel to the longitudinal first centerline 60 may be disposed at the top corner 33 of the cutting surface 35 of the cutting tooth 30. The distance between the first centerline 60 and the parallel line 63 may be used to define the tooth cutting height 66. The tooth height has been selected to provide a high efficiency cutting chain 10. A second set of centerlines 67 and 68 perpendicular to the longitudinal first centerline 60 may be disposed through the rivet hole 38 and used to define a distance 69 between the three rivets. The chain pitch is the average distance between two rivets. When the distance between the rivets varies, the pitch can be measured by taking a measurement between three rivets and dividing the distance by two. Thus, the pitch distance is distance 69 divided by two. In an embodiment, the ratio between the tooth height and the pitch distance has been selected to provide a high efficiency cutting chain 10. In an embodiment, the angle of the forward-most portion 24, as measured relative to line 60, is between about 35 ° and about 70 °. In an embodiment, the top edge 23 of the bumper portion 22 of the bumper drive link 20 slopes downward from the tip end 25 to the top portion 28 of the trailing edge 26. In an embodiment, the top edge 23 of the bumper portion 22 of the bumper drive link 20 is downwardly inclined at an angle between about-3 ° (upwardly inclined) to about 8 ° (downwardly inclined), e.g., 4.6 ° (downwardly inclined) as measured from line 60. The longitudinal first centerline 60 may be disposed through adjacent rivet holes 38. In an embodiment, when the chain 10 is in the first position 12 with its straight portion traversing the rod, the distance between the longitudinal first centerline 60 and the tip 25 is greater than the distance between the longitudinal first centerline 60 and the top portion 28 of the trailing edge 26. In various embodiments, the recesses 27 are sized to reduce the amount of drive link material protruding into the gullets 36 of the cutter link, which in turn reduces the impact on the flow of swarf through the gullets 36, thereby promoting better cutting performance. A second centerline 62, which is perpendicular to the longitudinal first centerline 60, may be disposed through the rivet hole 38. The second centerline 62 may be used to define a tail extension distance 64. In embodiments, the tail extension distance 64 is about 17% to about 23% (e.g., about 20%) of the distance between the rivet holes 38 of the cutter tooth link 20.

In various embodiments, the recesses 27 are sized to reduce the amount of drive link material protruding into the gullets 36 of the cutter link, which in turn reduces the impact on the flow of swarf through the gullets 36, thereby promoting better cutting performance. In some embodiments, the bumper portion 22 may be generally aligned with the upper surface of the depth gauge 34 at its point of maximum radial extension (e.g., extending radially from the center of the nose) as the bumper portion 22 traverses the nose. This alignment may have a greater surface area relative to the width of the cut, which may help resist recoil when traversing the nose. In other embodiments, the ends of the bumper portion 22 may extend radially further or less than the depth gauge.

Various embodiments may include the following proportions of saw chain components having preselected values: so that it may help maintain performance when in the first position 12 and minimize backlash when in the second position 14. The height of the top edge 23 of the bumper portion 22 above the centerline 60 of the rivet hole 38 may be expressed as the height of the tip 25 and may be varied as needed to improve performance, reduce backlash and improve chain maintainability. In various embodiments, the tip height may be a predetermined percentage of the depth gauge height 34, such as in the range of 80% to 100%. In other embodiments, the tip height may be kept below the depth gauge height, which may reduce the need for maintenance (e.g., filing) on the tail during the entire life of the saw chain.

Although certain embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent embodiments or implementations calculated to achieve the same purposes may be substituted for the embodiments shown and described without departing from the scope. Those with skill in the art will readily appreciate that the embodiments may be implemented in a very wide variety of ways.

This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that embodiments be limited only by the claims and the equivalents thereof.

Claims (12)

1. A high efficiency saw chain comprising:

a cutting link, the cutting link comprising:

front cutting link rivet holes;

post-cutting a chain link rivet hole;

an upper cutting edge disposed at a first height relative to a first line: the first line is collinear with a lowermost portion of the cutting link and parallel to a second line bisecting the front and rear cutting link rivet holes;

a depth gauge opposite the cutting edge, the depth gauge having an upper surface disposed at a second height, the second height being substantially at or below the first height;

a gullet formed between the cutting edge and the depth gauge; and a drive link, the drive link comprising:

a front drive link rivet hole; and

a rear drive link rivet hole to which the drive link is coupled via rivets that engage the front and rear drive link rivet holes, a chain pitch defined as half a distance between a center of the front drive link rivet hole and a center of the rear drive link rivet hole,

characterized in that a ratio between the first height and the chain pitch is selected for a given power range to provide a high efficiency saw chain, wherein the ratio between the first height and the chain pitch is between 1.22 and 1.28.

2. The high efficiency saw chain of claim 1, wherein the first height is between 0.400 inches and 0.412 inches.

3. The high efficiency saw chain of claim 1, wherein the chain pitch is between 0.315 inches and 0.335 inches.

4. The high efficiency saw chain of claim 1, wherein the given power range is 1 horsepower to 3 horsepower.

5. The high efficiency saw chain of claim 1, wherein the upper cutting edge is disposed at a third height relative to the second line bisecting the front and rear cutting link rivet holes, wherein a ratio between the third height and the chain pitch is between 0.86 and 0.92.

6. The high efficiency saw chain of claim 5, wherein the third height is between 0.285 inches and 0.295 inches.

7. The high efficiency saw chain of claim 1, wherein a ratio between the first height and the second height is selected to provide a high efficiency saw chain, wherein the ratio between the first height and the second height is between 1.05 and 1.10.

8. A system comprising the high efficiency saw chain of claim 1 and a drive sprocket configured to drive the high efficiency saw chain.

9. The system of claim 8, further comprising a guide bar configured to guide the high efficiency saw chain.

10. A power saw, characterized in that it comprises a high efficiency saw chain according to claim 1.

11. The power saw of claim 10, further comprising a drive sprocket configured to drive the high efficiency saw chain.

12. The power saw of claim 10, further comprising a guide bar configured to guide the high efficiency saw chain.

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