chain

Abstract

This design achieves both reduced friction against the chain guide and suppression of chain guide wear. [Solution] The timing chain 5 is made up of alternating inner links 13 and outer links 17. The inner plate 10 of the inner link 13 has a first sliding contact region S1 that slides against the guide and a non-sliding contact region SN that does not slide against the guide. The first sliding contact region S1 is formed in a range shorter than the chain pitch TP. In the first sliding contact region S1, the inner plate 10 has a greater height than the outer plate 15 in terms of height from the pitch line PL. In the non-sliding contact region SN, the outer plate 15 has a greater height than the inner plate 10. When the height of the inner plate 10 from the pitch line PL to the highest point MP1 in the first sliding contact region S1 is the first height h1, and the height of the outer plate 10 from the pitch line PL to the highest point MP2 in the non-sliding contact region SN is the second height h2, the relationship h1 > h2 is satisfied.

Description

Technical Field

[0006] , , , ,

[0001] The present invention relates to a chain for power transmission.

Background Art

[0002] A power transmission chain is known in which outer links, each having a pair of outer plates connected by pins, and inner links, each having a pair of inner plates connected by bushes, are alternately connected by inserting the pins into the bushes. Patent Document 1 discloses a chain that reduces friction loss against a chain guide by providing a sliding contact arc region on the back surface of the inner plate that slidably contacts the chain guide.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In this embodiment, since the relationship h1 > h2 exists, the first sliding contact area of ​​the inner plate preferentially slides against the guide rather than the outer plate. Furthermore, since the first sliding contact area is formed in a range shorter than the chain pitch, friction with the chain guide can be reduced. On the other hand, wear of the guide due to the sliding contact is unavoidable. Here, in the non-sliding area of ​​the inner plate, the outer plate has a greater height, so depending on the changes in the chain's running conditions, the outer plate can also slide against the guide. As a result, the surface pressure on the guide is distributed between the inner and outer plates, and the progression and unevenness of guide wear can be suppressed. Therefore, it is possible to achieve both a reduction in friction with the chain guide and a suppression of chain guide wear, providing a chain with excellent running stability over the long term.

[0008] In the above-described chain, it is desirable that the first sliding contact region has a length of 73% to 86% of the chain pitch in the direction along the pitch line.

[0009] According to this embodiment, since the length of the first sliding contact area relative to the chain pitch is set within the above range, it is possible to more effectively suppress the surface pressure that the first sliding contact area applies to the guide and to suppress the friction of the first sliding contact area relative to the guide.

[0010] In the chain described above, the first sliding contact region preferably includes a first arc extending on both sides of the center line of the inner plate in the direction along the pitch line, and a pair of second arcs extending outward from each end of the first arc, and the first height is preferably the height on the center line.

[0011] In particular, the radius of the first arc is larger than the radius of the second arc, and the length occupied by the portion of the first arc in the first sliding contact region is preferably 5% to 48% of the total length of the first sliding contact region in the direction along the pitch line.

[0012] Reducing friction against the guide and suppressing wear of the guide are inherently conflicting challenges. According to the above embodiment, it is possible to achieve a good balance between friction reduction and friction suppression.

[0013] In the above chain, it is desirable that the region of the outer plate including the portion of the second height h2 is a second sliding contact region including an arc that can slide against the guide.

[0014] According to this embodiment, even if the second sliding contact area of ​​the outer plate comes into contact with the guide due to the chain's movement conditions, friction with the guide can be suppressed because the second sliding contact area has a shape that includes an arc. Furthermore, since the second sliding contact area slides against the guide together with the first sliding contact area of ​​the inner plate, it can contribute to suppressing surface pressure on the guide and thus suppress wear of the guide.

[0015] In the chain described above, it is desirable that, in a side view of the chain, it has a recessed portion demarcated by a common tangent line connecting the arc constituting the first sliding contact region and the arc constituting the second sliding contact region, the outer contour line of the inner plate, and the outer contour line of the outer plate.

[0016] According to this embodiment, the recessed area can be utilized as a region for retaining lubricating oil. Therefore, the breakdown of the oil film on the chain can be suppressed, and as a result, wear on the guide can be suppressed.

[0017] In the above chain, it is desirable that the difference between the first height h1 and the second height h2 be in the range of 0.1 mm to 0.27 mm.

[0018] According to this embodiment, the surface pressure of the chain against the guide can be further suppressed. When a groove is formed in the guide due to wear caused by sliding contact in the first sliding contact area, the second sliding contact area also comes into sliding contact with the guide. By setting the difference between h1 and h2 to the above numerical range, the timing of the transition to a state where both the first and second sliding contact areas slide against the guide can be optimized, thereby suppressing the progression of guide wear. Consequently, stable chain operation can be maintained.

[0019] In the chain described above, it is preferable that the outer plate has a recess in the central region in the direction along the pitch line that is recessed toward the pitch line, and that the second sliding contact region is located at both ends of the recess.

[0020] In this embodiment, the outer plate has a shape with a recess between a pair of second sliding contact regions. Therefore, areas of the outer plate other than the second sliding contact regions are less likely to come into contact with the guide. Consequently, even when the radius of curvature of the guide is relatively small, for example, the central region of the outer plate is less likely to come into contact with the guide. Therefore, friction with respect to the guide is easily reduced. [Effects of the Invention]

[0021] According to the present invention, it is possible to provide a chain that can achieve both reduction of friction with a chain guide and suppression of wear of the chain guide.

Brief Description of the Drawings

[0022] [Figure 1] FIG. 1 is a front view showing an example of a timing chain transmission device. [Figure 2] FIG. 2 is a partially broken-away plan view of a timing chain which is an embodiment of the chain according to the present invention. [Figure 3] FIG. 3 is a side view of the timing chain shown in FIG. 2. [Figure 4] FIG. 4 is an enlarged view of the main part of FIG. 3 with the first height h1 and the second height h2 added. [Figure 5] FIG. 5 is an enlarged view of the main part of FIG. 4 for explaining a recessed portion for storing oil. [Figure 6] FIGS. 6(A) to (C) are schematic views for explaining the contact state of the timing chain of the present embodiment with respect to the shoe. [Figure 7] FIG. 7 is a view showing the sliding state of the timing chain of the present embodiment with respect to the guide member.

Mode for Carrying Out the Invention

[0023] Hereinafter, embodiments of the present invention will be described in detail based on the drawings. The chain according to the present invention is a power transmission chain applicable to a power transmission mechanism incorporated in a moving vehicle such as a four-wheel or two-wheel automobile, or a heavy machine or an industrial machine. In the embodiments shown below, as an example of the chain according to the present invention, a timing chain assembled to an engine of an internal combustion engine will be exemplified.

[0024] [Configuration of Timing Chain Transmission Device] Figure 1 is a front view showing an example of a timing chain transmission device 1. The timing chain transmission device 1 is installed, for example, in an engine for an automobile. The engine is a power source for driving the automobile and includes a cylinder and piston (not shown), a crankshaft 2, and a pair of camshafts 3. The crankshaft 2 is connected to the piston and is rotationally driven around its axis in accordance with the reciprocating motion of the piston within the cylinder. The two camshafts 3 open and close intake and exhaust valves attached to the cylinder, respectively. The camshafts 3 rotate in conjunction with the rotation of the crankshaft 2.

[0025] The timing chain transmission system 1 includes a crank sprocket 2a, a pair of cam sprockets 3a, a guide member 4, and a timing chain 5. The crank sprocket 2a is mounted on the shaft end of the crankshaft 2 and rotates integrally with the crankshaft 2. The pair of cam sprockets 3a are each mounted on the shaft ends of a pair of camshafts 3 and rotate integrally with the camshafts 3. The timing chain 5 is wound between the crank sprocket 2a and the pair of cam sprockets 3a. The timing chain 5 transmits power from the crankshaft 2 to the camshafts 3. That is, the rotation of the crank sprocket 2a causes the timing chain 5 to rotate, and as a result the cam sprockets 3a rotate, thereby transmitting power from the crankshaft 2 to the camshafts 3.

[0026] The guide member 4 is positioned on the outer circumference of the timing chain 5 and serves as a guide to guide the rotational movement of the timing chain 5. The guide member 4 includes a first chain guide 6, a second chain guide 7, and a tensioner arm 8. The outer circumference of the timing chain 5 slides against each of the guide members 4, thereby suppressing the oscillation of the timing chain 5 and ensuring stable rotational movement.

[0027] As shown by the arrow in Figure 1, when the timing chain 5 rotates clockwise, the space between the crank sprocket 2a and the left camshaft sprocket 3a is the slack side of the timing chain 5, and the remaining space is the tension side due to the driving load of the camshaft 3. Chain guides 6 and 7 are positioned on the tension side, and a tensioner arm 8 is positioned on the slack side. Chain guides 6 and 7 are fixed to the engine block. The tensioner arm 8 is a member that applies tension to the timing chain 5 and includes a shoe 8a and a support shaft 8b. The shoe 8a slides against the timing chain 5. The support shaft 8b is attached to the engine block and pivotably supports one end of the tensioner arm 8. The plunger of the chain tensioner 9 abuts against the other end of the tensioner arm 8. Appropriate tension is applied to the timing chain 5 from the chain tensioner 9 via the tensioner arm 8.

[0028] [Overall Timing Chain Configuration] Let's explain the overall structure of the timing chain 5. Figure 2 is a partially broken plan view of the timing chain 5, and Figure 3 is a side view of the timing chain 5. The timing chain 5 is an endless structure made up of multiple inner links 13 and multiple outer links 17 that are alternately connected. The inner links 13 include a pair of inner plates 10, a pair of bushings 11, and a pair of rollers 12. The outer links 17 include a pair of outer plates 15 and a pair of pins 16. Note that Figure 3 shows a side view with one outer plate 15, a bushing 11, and a pin 16 removed. Also, in the side view, in reality, most of the inner plate 10 is covered by the outer plate 15 and not visible, but in Figure 3, it is shown as visible for the sake of explanation. The inner plates 10 are shown with thick lines, and the outer plates 15 are shown with thin lines.

[0029] The pair of inner plates 10 both have a substantially elliptical shape when viewed from the side and are arranged parallel to each other. A first bushing hole 10a is drilled at one end of the inner plate 10 in the longitudinal direction, and a second bushing hole 10b is drilled at the other end. The pair of inner plates 10 are connected by pressing both ends of a pair of bushings 11 into the bushing holes 10a and 10b, respectively. The bushings 11 have through holes 11a through which pins 16 are inserted. The roller 12 is rotatably fitted onto the bushings 11 between the pair of inner plates 10.

[0030] The pair of outer plates 15 both have a shape similar to the number "8" when viewed from the side, with a depression in the center along their longitudinal direction, and are arranged parallel to each other with the inner links 13 in between. A first pin hole 15a is drilled at one end of the outer plate 15 in the longitudinal direction, and a second pin hole 15b is drilled at the other end. The pair of outer plates 15 are connected by pressing both ends of a pair of pins 16 into the pin holes 15a and 15b and then fixing them by crimping. The pins 16 are inserted through the through hole 11a, with both ends fixed to the pin holes 15a and 15b. The inner links 13 and outer links 17 are alternately connected by inserting the pins 16 through the through hole 11a.

[0031] [Detailed configuration of the timing chain] The configuration of the timing chain 5 will be described in more detail, referring to Figure 4, which is an enlarged view of the main part of Figure 3. The inner plate 10 has a substantially elliptical shape that is symmetrical with respect to the pitch line PL as the axis of symmetry. The pitch line PL is the line connecting the centers Oa and Ob, where Oa is the center of the first pin hole 15a and Ob is the center of the second pin hole 15b, which are opened in the outer plate 15. The longitudinal direction of the inner plate 10 and the outer plate 15 is the direction in which the pitch line PL extends. The chain pitch TP of the timing chain 5 is the length between the above-mentioned centers Oa and Ob. In this embodiment, it is described as having a symmetrical shape with respect to the pitch line PL as the axis of symmetry, but it is not necessary for it to be symmetrical.

[0032] The outer surface of the inner plate 10 on the outer side of the pitch line PL of the timing chain 5 is the back surface 10R that slides against the guide member 4. The inner surface 10Q of the inner plate 10 on the inner side of the pitch line PL is the inner surface that does not slide against the guide member 4. The back surface 10R and the inner surface 10Q are symmetrical in shape with respect to the pitch line PL. Furthermore, the inner plate 10 has a symmetrical shape with respect to the center line LC in the shorter direction that extends perpendicular to the pitch line PL at a position half the pitch of the chain pitch TP.

[0033] The inner plate 10 has a first sliding contact area S1 and a non-sliding contact area SN on its back surface 10R. The first sliding contact area S1 slides against the guide member 4 that guides the timing chain 5 when the timing chain 5 is driven. On the other hand, the non-sliding contact area SN is an area that does not slide against the guide member 4 even when the timing chain 5 is driven. The first sliding contact area S1 is a fixed area in the longitudinal direction of the inner plate 10 centered on the center line LC. The non-sliding contact area SN is located to the right and left of the first sliding contact area S1.

[0034] The first sliding contact area S1 is formed in a range shorter than the chain pitch TP. This range setting of the first sliding contact area S1 is intended to reduce friction with respect to the guide member 4. However, if the length of the first sliding contact area S1 is too short, the surface pressure applied to the guide member 4 will increase, causing, for example, premature wear of the shoe 8a of the tensioner arm 8. In other words, friction reduction and suppression of guide member wear are two sides of the same coin. In view of this, it is desirable to set the length of the first sliding contact area S1 to 73% to 86% of the chain pitch TP in the direction along the pitch line PL. This length setting allows for a good balance between friction reduction and wear suppression.

[0035] The first sliding contact region S1 is composed of multiple arcs with the same bulging direction. Specifically, it is composed of a first arc R1 extending to the left and right sides of the center line LC, and a pair of second arcs R2 extending outward from each end of the first arc R1. Both the first arc R1 and the second arc R2 are arcs that bulge away from the pitch line PL, that is, towards the outer circumference. The first arc R1 is an arc with a relatively large radius. The radius of the second arc R2 is also larger than the radius of the first arc R1. Figure 3 shows the R1 region composed of the first arc R1 and the R2 region composed of the second arc R2 on the back surface 10R.

[0036] The R1 region is located near the center line LC. The R2 region to the right of the R1 region extends from the right end of the R1 region to a position beyond line La, which passes through the center Oa of the first pin hole 15a and is perpendicular to the pitch line PL. A third arc R3, which is concentric with the bushing hole 10a, is connected to the right end of this R2 region. The R2 region to the left of the R1 region extends from the left end of the R1 region to a position beyond line Lb, which passes through the center Ob of the second pin hole 15b and is perpendicular to the pitch line PL. A third arc R3 on the left is connected to the left end of this R2 region. For example, the radius of the first arc R1 is 100 mm, the radius of the second arc R2 is 20 mm, and the radius of the third arc is 3.5 mm.

[0037] The first sliding contact region S1 is composed of a first circular arc R1 and parts of two second circular arcs R2. The length of the portion of the first circular arc R1 in the first sliding contact region S1 is preferably 5% to 48% of the total length of the first sliding contact region S1 in the direction along the pitch line PL. By arranging a first circular arc R1 with a large radius, that is, a small degree of curvature, for a length within the above range, a good balance between friction reduction and friction suppression can be achieved. The first sliding contact region S1 may be formed by a series of circular arcs that bulge out in the direction away from the pitch line PL, and may be formed by a series of three or more circular arcs. In addition, a short straight section connecting the series of circular arcs may be included in a part of the first sliding contact region S1.

[0038] The outer plate 15 includes a pair of circular portions 151 located around a pair of pin holes 15a and 15b, and a recess 152 located in the central region between the pair of circular portions 151. The outer plate 15 has a symmetrical shape on the back surface 10R side and the inner surface 10Q side with respect to the pitch line PL. The outer plate 15 also has a symmetrical shape on the left and right sides with respect to a center line extending perpendicular to the pitch line PL at a position half a pitch of the chain pitch TP. The recess 152 is recessed toward the pitch line PL. Due to the presence of the recess 152, the outer plate 15 has a contoured shape with a constricted central region in the direction along the pitch line PL.

[0039] The outer plate 15 is provided with second sliding contact areas S2 at both ends of the recess 152 that can slide against the guide member 4. The second sliding contact area S2 is composed of a portion of a plurality of arcs that make up the circular portion 151. The portion of the plurality of arcs is the arc portion adjacent to the recess 152. As shown in Figure 3, in a side view, the second sliding contact area S2 is located in the region corresponding to the non-sliding contact area SN of the inner plate 10 and is located on both sides of the first sliding contact area S1.

[0040] The height relationship between the first sliding contact region S1 and the second sliding contact region S2 from the pitch line PL will be explained with reference to Figure 4, which is an enlarged view of the main part of Figure 3. In the first sliding contact region S1, the inner plate 10 has a greater height than the outer plate 15 in terms of height from the pitch line PL. On the other hand, in the non-sliding contact region SN, the outer plate 15 has a greater height than the inner plate 10 in terms of height from the pitch line PL.

[0041] The first height h1 is defined as the height from the pitch line PL of the inner plate 10 to the highest point MP1 in the first sliding contact region S1. The second height h2 is defined as the height from the pitch line PL of the outer plate 15 to the highest point MP2 in the non-sliding contact region SN. In this embodiment, the highest point MP1 is located within the R1 region of the first arc R1 and on the center line LC. That is, the first height h1 is the height of the inner plate 10 on the center line LC. In this embodiment, the highest point MP2 is located on lines La and Lb that pass through the centers Oa and Ob of the pin holes 15a and 15b and are perpendicular to the pitch line PL. The arc portion of the outer plate 15 including the highest point MP2 and its vicinity becomes the second sliding contact region S2 described above. The positions of the highest points MP1 and MP2 are not limited to this embodiment. The highest points MP1 and MP2 may be located at positions shifted in the direction of the pitch line PL from the center line LC and lines La and Lb.

[0042] The first height h1 and the second height h2 are set to satisfy the relationship h1 > h2. When the relationship h1 > h2 is met, the first sliding contact region S1 of the inner plate 10 has priority over the outer plate 15 in sliding contact with the guide member 4. In other words, the inner plate 10 protrudes from the outer plate 15 by a height difference Δh = h1 - h2. More specifically, the portion of the inner plate 10 that protrudes toward the shoe 8a side from the imaginary line SL connecting the highest points MP2 of adjacent outer plates 15 is defined as the first sliding contact region S1. Therefore, the first sliding contact region S1 has priority over the second sliding contact region S2 in contact with the shoe surface of the guide member 4. In this embodiment, the first sliding contact region S1 is formed in a range shorter than the chain pitch TP, so friction with the guide member 4 can be reduced. The height difference Δh, which is the difference between h1 and h2, can be set as appropriate, but for example, it can be set in the range of 0.1 mm to 0.27 mm.

[0043] The timing chain 5 is provided with a recess 18 for storing lubricating oil. Figure 5 is an enlarged view of the main part of Figure 4 to illustrate the recess 18. Figure 5 shows a hypothetical common tangent line TL connecting the arc constituting the first sliding contact region S1 and the arc constituting the second sliding contact region S2. In a side view of the timing chain 5, the recess 18 is demarcated by the above-mentioned common tangent line TL, the outer contour line of the inner plate 10, and the outer contour line of the outer plate 15. The recess 18 is located between the first sliding contact region S1 and the second sliding contact region S2 and is a roughly V-shaped recess with a large opening width, whose deepest point is the intersection IN of the outer contour lines of the inner plate 10 and the outer plate 15.

[0044] The recessed portion 18 can be used as a lubrication oil retention area. In this embodiment, the first sliding contact region S1, which has the highest height from the pitch line PL, is formed in a range shorter than the chain pitch TP, resulting in a smaller contact area with the guide member 4. As a result, the contact pressure at the contact point where the first sliding contact region S1 contacts the guide member 4 increases, and the oil film thickness of the lubricating oil interposed between them tends to become thinner. In this embodiment, there is a recessed portion 18 between the first sliding contact region S1 and the second sliding contact region S2 where lubricating oil can be retained. The oil reservoir formed in this recessed portion 18 can be used as a source of lubricating oil for the first sliding contact region S1. Therefore, oil film breakdown of the timing chain 5 can be suppressed, and as a result, wear of the guide member 4 can be suppressed.

[0045] [Regarding achieving both friction reduction and suppression of guide wear] The timing chain 5 of this embodiment makes it possible to achieve both a reduction in friction with respect to the guide member 4 and suppression of wear of the guide member 4. This point will be explained with reference to Figure 6. Figure 6(A) shows the timing chain 5 and the shoe 8a of the tensioner arm 8, which is one of the guide members 4. Figures 6(B) and (C) are enlarged views of the A1 portion of Figure 6(A). Figure 6(B) is a schematic diagram showing the contact situation of the timing chain 5 with the shoe 8a in the initial stages of use of the timing chain transmission device 1, and Figure 6(C) is a schematic diagram showing the contact situation after wear of the shoe 8a has progressed.

[0046] As shown in Figure 4, the first height h1 of the first sliding contact area S1 and the second height h2 of the second sliding contact area S2 are in the relationship h1 > h2. Therefore, in the initial stage of use shown in Figure 6(B), the first sliding contact area S1 of the inner plate 10 preferentially makes sliding contact with the shoe 8a as a guide, rather than the second sliding contact area S2 of the outer plate 15. Here, the length of the first sliding contact area S1 in the direction along the pitch line PL is set to a length of 73% to 86% of the chain pitch TP. Thus, it is possible to achieve a good balance between reducing friction of the timing chain 5 with respect to the shoe 8a and suppressing wear of the guide member 4.

[0047] Although friction reduction and wear suppression are well balanced, the shoe 8a gradually wears down due to the sliding contact with the timing chain 5. As shown in Figure 6(C), this wear causes a shoe groove 8G to be formed on the shoe 8a, which is cut away by the first sliding contact area S1 of the inner plate 10.

[0048] In the non-sliding region SN of the inner plate 10, the outer plate 15 has a greater height. Therefore, as wear progresses on the shoe 8a and the shoe groove 8G deepens, the second sliding region S2 of the outer plate 15 also comes into sliding contact with the shoe 8a. In other words, as wear progresses as shown in Figure 6(C), the first sliding region S1 and the second sliding region S2 come into sliding contact with the shoe 8a. As a result, the surface pressure on the shoe 8a is distributed between the inner plate 10 and the outer plate 15, which suppresses the progression of wear and uneven wear of the shoe 8a.

[0049] Even when both the inner plate 10 and the outer plate 15 are in contact with the shoe 8a, the shape of the outer plate 15 contributes to friction reduction. The upper part of Figure 7 is a side view of the outer plate 15 alone, and the lower part of Figure 7 is a diagram showing the sliding contact state between the guide member 40 with a small radius of curvature and the timing chain 5. As described above based on Figure 3, the outer plate 15 includes a pair of circular parts 151 with pin holes 15a and 15b, and a recess 152 which is a constriction between the pair of circular parts 151. The second sliding contact region S2 is located on both sides of the recess 152.

[0050] As shown in Figure 6(C), even when the shoe groove 8G deepens to the point where the outer plate 15 slides against the shoe 8a, only the arc portion forming the second sliding contact region S2 actually contacts the shoe 8a on the outer plate 15. This is because the outer plate 15 is not an elliptical shape with a bulge on the longer side, but rather has a constricted recess 152 between the pair of second sliding contact regions S2. Because the outer plate 15 has a constricted shape, even when the timing chain 5 is guided by a guide member 40 with a small radius of curvature, the recess 152 does not become a sliding contact area, and only the arc portion of the second sliding contact region S2 actually slides against the shoe. Moreover, the second sliding contact region S2 is formed in an arc shape with the highest point MP2 of the outer plate as its apex. Therefore, even when wear progresses to the point where not only the inner plate 10 but also the outer plate 15 slides against the guide member, the increase in friction can be suppressed.

[0051] According to this embodiment, as described above, it is possible to achieve both a reduction in friction with respect to the guide member 4 including the shoe 8a and a suppression of wear of the guide member 4, thereby providing a timing chain 5 with excellent running stability over a long period of time. In particular, if the length of the first sliding contact area S1 in the direction along the pitch line PL is set to a length of 73% to 86% of the chain pitch TP, it is possible to achieve even better suppression of the surface pressure that the first sliding contact area S1 applies to the guide member 4 and suppression of friction with respect to the guide member 4. [Explanation of Symbols]

[0052] 1. Timing chain transmission system 4 Guide members (guides) 5 Timing chain (chain) 6, 7 Chain guide 8 Tensioner Arm 8a Shoe (guide) 10 Inner plate 10 10a, 10b bushing holes 10R back 11 Bush 12 Laura 13 Internal Links 15 Outer plate 15a, 15b pin hole 152 recess 16 pins 17 External Links 18 Recessed area h1 First height h2 Second height TP chain pitch MP1, MP2 Highest score PL Pitch Line S1 1st sliding contact area S2 2nd sliding contact area SN Non-sliding area R1 First arc R2 Second arc LC center line TL common tangent

Claims

1. A chain comprising a plurality of outer links, each including a pair of outer plates and a pair of pins connecting the pair of outer plates, and a plurality of inner links, each including a pair of inner plates and a pair of bushings connecting the pair of inner plates, wherein the outer links and the inner links are alternately connected by inserting the pins into the bushings, The inner plate includes a back surface having a first sliding contact area that slides against a guide that guides the chain when the chain is driven, and a non-sliding contact area that does not slide against the guide. The first sliding contact region is formed by a plurality of arcs with the same bulging direction, over a range shorter than the chain pitch. In the first sliding contact region, the inner plate has a greater height than the outer plate in terms of the height from the pitch line connecting the centers of the pair of pin holes through which the pair of pins are provided in the outer plate. In the non-sliding region, the outer plate has a greater height than the inner plate in terms of height from the pitch line. A chain that satisfies the relationship h1 > h2, where h1 is the height from the pitch line to the highest point of the inner plate in the first sliding contact region, and h2 is the height from the pitch line to the highest point of the outer plate in the non-sliding contact region.

2. In the chain according to claim 1, The first sliding contact region is a chain having a length of 73% to 86% of the chain pitch in the direction along the pitch line.

3. In the chain according to claim 1, The first sliding contact region includes a first circular arc extending on both sides of the center line of the inner plate in the direction along the pitch line, and a pair of second circular arcs extending outward from each end of the first circular arc. The chain, wherein the first height is the height along the center line.

4. In the chain described in claim 3, The radius of the first arc is greater than the radius of the second arc. A chain in which the length of the first arc portion in the first sliding contact region is 5% to 48% of the total length of the first sliding contact region in the direction along the pitch line.

5. In the chain according to any one of claims 1 to 4, A chain in which the region of the outer plate including the portion of the second height h2 is a second sliding contact region including an arc that can slide against the guide.

6. In the chain according to claim 5, A chain having, in a side view, a common tangent line connecting the arc constituting the first sliding contact region and the arc constituting the second sliding contact region, the outer contour line of the inner plate, and the outer contour line of the outer plate, respectively.

7. In the chain according to any one of claims 1 to 4, A chain in which the difference between the first height h1 and the second height h2 is in the range of 0.1 mm to 0.27 mm.

8. In the chain according to claim 5, The chain wherein the outer plate has a recess in the central region in the direction along the pitch line that is recessed toward the pitch line, and the second sliding contact regions are located at both ends of the recess.

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