Chain

Abstract

A chain is formed by alternating inner and outer links. An inner plate of the inner link has a first sliding contact area, which is in sliding contact with a guide, and a non-sliding contact area, which is not in sliding contact with the guide. The first sliding contact area is formed over a span shorter than one chain pitch. In the first sliding contact area, the inner plate has a height greater than the height of an outer plate with respect to a pitch line. In the non-sliding contact area, the outer plate has a height greater than the height of the inner plate.If a height from the dividing line to a highest point of the inner plate in the first sliding contact area is defined as a first height h1 and a height from the dividing line to a highest point of the outer plate in the non-sliding contact area is defined as a second height h2, then a relationship of h1 > h2 is satisfied.

Description

Field of invention

[0001] The present invention relates to a chain for power transmission. State of the art

[0002] A power transmission chain is known in which an outer link, where a pair of outer plates are connected by a pin, and an inner link, where a pair of inner plates are connected by a bushing, are alternately connected by inserting the pin into the bushing. Japanese Patent No. 5259775 discloses a chain that reduces frictional losses with respect to a chain guide by providing a sliding contact arc area in sliding contact with the chain guide on a rear surface of the inner plate.

[0003] In the chain described in Japanese patent no. 5259775, the sliding contact arc area is specified to be longer than one chain pitch. However, if the width of the sliding contact area of ​​the chain relative to the chain guide is too long, there is a situation where friction cannot be sufficiently reduced. Conversely, if the width of the sliding contact area is reduced, the surface pressure exerted by the chain on the chain guide increases, and wear of the sliding contact surface of the chain guide can easily progress. Brief description of the invention

[0004] One object of the present invention is to provide a chain that is capable of achieving both a reduction of friction with respect to a chain guide and a suppression of wear of the chain guide.

[0005] A chain according to one aspect of the present invention is a chain comprising a plurality of outer links, each comprising a pair of outer plates and a pair of pins connecting the pair of outer plates, and a plurality of inner links, each comprising 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, wherein the inner plate comprises a rear surface having a first sliding contact area, which comes into sliding contact with a guide that guides the chain when the chain is driven, and a non-sliding contact area, which does not come into sliding contact with the guide, the first sliding contact area being formed in a span shorter than one chain pitch, by a plurality of arcs curving in the same direction.In the first sliding contact area, the inner plate has a height greater than the height of the outer plate with respect to a height from a division line connecting the centers of a pair of pin holes open in the outer plate through which the pair of pins passes; in the non-sliding contact area, the outer plate has a height greater than the height of the inner plate with respect to a height from the division line; and if a height from the division line to a highest point of the inner plate in the first sliding contact area is defined as a first height h1, and a height from the division line to a highest point of the outer plate in the non-sliding contact area is defined as a second height h2, then the relationship h1 > h2 is satisfied. Brief description of the drawings Fig. Figure 1 is a front view showing an example of a timing chain transmission device; Fig. 2 is a partially cutaway top view of a timing chain, which is an embodiment of a chain according to the present invention; Fig. 3 is a side view of the timing chain, which is located in Fig. 2 is shown; Fig. 4 is an enlarged view of a main part of Fig. 3, where the first height h1 and the second height h2 are added; Fig. 5 is an enlarged view of a main part of Fig. 4 to describe a sunken section for storing oil; Fig. Figure 6 shows schematic diagrams to describe a contact state of the control chain of the present embodiment with respect to a shoe; and Fig. Figure 7 is a diagram illustrating a sliding state of the timing chain of the present embodiment with respect to a guide element. Detailed description

[0006] An embodiment of the present disclosure is described in detail below with reference to the drawings. A chain according to the present invention is a power transmission chain applicable to a power transmission mechanism installed in a moving vehicle, such as a four-wheeled or two-wheeled automobile, heavy machinery, industrial machinery, or the like. In the embodiment described below, a timing chain attached to an internal combustion engine is described by way of example as the chain according to the present invention. [Design of a timing chain transmission device]

[0007] Fig. Figure 1 is a front view illustrating an example of a timing chain transmission device 1. The timing chain transmission device 1 is, for example, attached to an automotive engine. The engine is a power source for propelling an automobile and comprises 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 driven to rotate about an axis in accordance with a reciprocating motion of the piston within the cylinder. Two of the camshafts 3 drive the opening and closing of an intake valve and an exhaust valve, respectively, which are attached to the cylinder. The camshaft 3 rotates in conjunction with the rotation of the crankshaft 2.

[0008] The timing chain transmission device 1 comprises a crank pinion 2a, a pair of cam pinions 3a, a guide element 4, and a timing chain 5. The crank pinion 2a is mounted on an axial end of the crankshaft 2 and rotates in unison with the crankshaft 2. A pair of cam pinions 3a are mounted on an axial end of a pair of camshafts 3 and rotate in unison with the camshafts 3. The timing chain 5 is wound between the crank pinion 2a and a pair of cam pinions 3a. The timing chain 5 transmits power from the crankshaft 2 to the camshaft 3. That is, the timing chain 5 rotates as the crank pinion 2a rotates, and the cam pinion 3a is driven to rotate by the rotation of the timing chain 5, thus transmitting power from the crankshaft 2 to the camshaft 3.

[0009] The guide element 4 is arranged on the outer circumference of the timing chain 5 and serves as a guide for the rotation of the timing chain 5. The guide element 4 comprises a first chain guide 6, a second chain guide 7, and a tensioning arm 8. When the outer circumferential side of the timing chain 5 comes into sliding contact with each of the guide elements 4, oscillation of the timing chain 5 is suppressed and stable rotation is ensured.

[0010] As if through an arrow in Fig. As shown in Figure 1, in a case where the timing chain 5 rotates clockwise, the section between the crankshaft sprocket 2a and one of the left cam sprockets 3a is the slack side of the timing chain 5, and the remaining section is the tensioned side, due to the application of a drive load by the camshaft 3. The chain guides 6 and 7 are located on the tensioned side, and the tensioning arm 8 is located on the slack side. The chain guides 6 and 7 are fixed to a power unit block. The tensioning arm 8 is an element that applies tension to the timing chain 5 and comprises a shoe 8a and a support shaft 8b. The shoe 8a is in sliding contact with the timing chain 5. The support shaft 8b is attached to a power unit block and pivotably supports one end of the tensioning arm 8. A plunger of a chain tensioner 9 is engaged with another end of the tensioning arm 8.The chain tensioner 9 applies appropriate tension to the timing chain 5 by means of the tensioning arm 8. [Overall design of a timing chain]

[0011] The overall design of the timing chain 5 is described. Fig. 2 is a partially cutaway top view of the timing chain 5 and Fig. Figure 3 is a side view of the timing chain 5. The timing chain 5 is an endless assembly in which a plurality of inner links 13 and a plurality of outer links 17 are alternately connected. The inner link 13 comprises a pair of inner plates 10, a pair of bushings 11, and a pair of rollers 12. The outer link 17 comprises a pair of outer plates 15 and a pair of pins 16. It should be noted that Fig. Figure 3 shows a side view of a state in which one of the outer plates 15, the bushing 11, and the pin 16 are removed. Furthermore, in a side view, most of the inner plate 10 is covered by the outer plate 15 and cannot be seen in practice, but in Fig. Figure 3 shows it as visible for a practical description. The inner plate 10 is indicated by a thick line and the outer plate 15 is indicated by a thin line.

[0012] Both inner plates 10 of a pair have a substantially elliptical shape in a side view and are arranged parallel to each other. A first bushing hole 10a is formed on one end face along a longitudinal direction of the inner plate 10, and a second bushing hole 10b is formed on the other end face. Both ends of a pair of bushings 11 are press-fitted into the bushing holes 10a and 10b, thus connecting a pair of inner plates 10. The bushing 11 has a through hole 11a through which the pin 16 is inserted. The roller 12 is rotatably fitted to the outside of the bushing 11 between a pair of inner plates 10.

[0013] Both outer plates 15 of a pair have a shape resembling the number "8", with the center recessed in one longitudinal direction in a side view, and are arranged parallel to each other, with the inner link 13 positioned between them. A first pin hole 15a is formed on one end face along one longitudinal direction of the outer plate 15, and a second pin hole 15b is formed on the other end face. Both ends of a pair of pins 16 are press-fitted into the pin holes 15a and 15b and then fixed by rivets, thus connecting a pair of outer plates 15. Both end sections of the pin 16 are fixed at the pin holes 15a and 15b in a position where they are inserted into the through-hole 11a. By inserting the pin 16 into the through-hole 11a, the inner link 13 and the outer link 17 are alternately connected. [Precise design of the timing chain]

[0014] The design of the timing chain 5 will be explained in more detail with reference to Fig. 4 described, which shows an enlarged view of a main part of Fig. 3. The inner plate 10 has a substantially elliptical shape, symmetrical about a division line PL as an axis of symmetry. If the center of the first pin hole 15a, open in the outer plate 15, is Oa and the center of the second pin hole 15b is Ob, then the division line PL is a line connecting the centers Oa and Ob. Note that the longitudinal direction of the inner plate 10 and the outer plate 15 is a direction in which the division line PL extends. A chain pitch TP of the control chain 5 is a length between the center Oa and the center Ob. Note that in the present embodiment, the description is given under the assumption that the shape is symmetrical with the division line PL as an axis of symmetry, but the shape need not be symmetrical.

[0015] A circumferential surface of the inner plate 10 on the outer circumferential side with respect to the pitch line PL of the timing chain 5 is a rear surface 10R in sliding contact with the guide element 4. A circumferential surface of the inner plate 10 on the inner circumferential side with respect to the pitch line PL is an inner surface 10Q, which is not in sliding contact with the guide element 4. The rear surface 10R and the inner surface 10Q have symmetrical shapes with respect to the pitch line PL. Furthermore, the inner plate 10 has a left-right symmetry shape with respect to a center line LC in a lateral direction that extends in a direction orthogonal to the pitch line PL at a position of half a pitch of the chain pitch TP, where the center line LC is an axis of symmetry.

[0016] The inner plate 10 has a first sliding contact area S1 and a non-sliding contact area SN on the rear surface 10R. The first sliding contact area S1 is in sliding contact with the guide element 4, which guides the timing chain 5 when the timing chain 5 is driven. In contrast, the non-sliding contact area SN is an area that does not come into sliding contact with the guide element 4, even when the timing chain 5 is driven. The first sliding contact area S1 is a specific area in the longitudinal direction of the inner plate 10 around the center line LC. The non-sliding contact area SN lies on the right and left sides of the first sliding contact area S1.

[0017] The first sliding contact area S1 is configured with a length shorter than the chain pitch TP. This shortening of the first sliding contact area S1 is intended to reduce friction with respect to the guide element 4. However, if the length of the first sliding contact area S1 is too short, the surface pressure applied to the guide element 4 increases, and, for example, the shoe 8a of the tensioning arm 8 will wear prematurely. In other words, reducing friction and suppressing wear of the guide element are mutually exclusive. With this in mind, the first sliding contact area S1 is preferably configured with a length of 73% to 86% of the chain pitch TP, with a length in one direction along the pitch line PL. This length configuration allows for a well-balanced reduction of both friction and wear.

[0018] The first sliding contact area S1 comprises a multitude of arcs that bulge in the same direction. Specifically, it includes a first arc R1, extending across the center line LC to both the left and right sides, and a pair of second arcs R2, extending outward from both ends of the first arc R1. Both the first arc R1 and the second arc R2 bulge away from the division line PL, that is, toward the outer circumferential side. The first arc R1 has a relatively large radius. The radius of the first arc R1 is larger than the radius of the second arc R2. Fig. 3 represents an R1 region formed by the first arc R1 and an R2 region formed by the second arc R2, on the rear surface 10R.

[0019] The R1 area lies near the center line LC. The R2 area on the right side of the R1 area extends from a right end of the R1 area to a position beyond a line La that passes through the center Oa of the first pin hole 15a and is orthogonal to the division line PL. A third arc R3, formed from an arc concentric with the socket hole 10a, is continuous at a right end of the R2 area. The R2 area on the left side of the R1 area extends from a left end of the R1 area to a position beyond a line Lb that passes through the center Ob of the second pin hole 15b and is orthogonal to the division line PL. The third arc R3 on the left side is continuous at a left end of the R2 area. 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 R3 is 3.5 mm.

[0020] The first sliding contact area S1 comprises the first arc R1 and a portion of two of the second arcs R2. The length occupied by the first arc R1 within the first sliding contact area S1 is preferably 5% to 48% of the total length of the first sliding contact area S1 in one direction along the parting line PL. By arranging an arc with a large radius, i.e., the first arc R1 with a small degree of curvature, with a length within the aforementioned range, friction reduction and wear suppression can be achieved in a well-balanced manner. The first sliding contact area S1 need only be formed by the continuous provision of a plurality of arcs that curve in one direction away from the parting line PL, and may be formed by the continuous provision of three or more arcs.Furthermore, a short straight section connecting a multitude of arcs may be included in part of the first sliding contact area S1.

[0021] The outer plate 15 comprises a pair of circular segments 151 surrounding a pair of pin holes 15a and 15b, and a recessed section 152 located in a central region between a pair of circular segments 151. The outer plate 15 has a symmetrical shape with respect to the division line PL between the side of the back surface 10R and the side of the inner surface 10Q. Furthermore, the outer plate 15 has a left-right symmetry shape with respect to a center line extending orthogonally to the division line PL at a position of half a division of the chain pitch TP, the center line being an axis of symmetry. The recessed section 152 is recessed in the direction of the division line PL. The outer plate 15 has a contour shape in which a central region is narrowed in one direction along the division line PL by the presence of the recessed section 152.

[0022] The outer plate 15 comprises second sliding contact areas S2, which come into sliding contact with the guide element 4, at both end sections of the recessed section 152. The second sliding contact area S2 is formed by a portion of a plurality of arcs that form the circular segment 151. A portion of a plurality of arcs is an arc segment that is adjacent to the recessed section 152. As in Fig. As shown in Figure 3, in a side view the second sliding contact area S2 lies in an area that corresponds to the non-sliding contact area SN of the inner plate 10 and lies on both sides of the first sliding contact area S1.

[0023] A height relationship between the first sliding contact area S1 and the second sliding contact area S2 from the division line PL is established with reference to Fig. 4 described, which shows an enlarged view of a main part of Fig. 3. In the first sliding contact area S1, the inner plate 10 has a greater height than the outer plate 15 with respect to a height from the division line PL. In contrast, in the non-sliding contact area SN, the outer plate 15 has a greater height than the inner plate 10 with respect to a height from the division line PL.

[0024] A height from the division line PL to a highest point MP1 of the inner plate 10 in the first sliding contact area S1 is defined as a first height h1. A height from the division line PL to a highest point MP2 of the outer plate 15 in the non-sliding contact area SN is defined as a second height h2. In the present embodiment, the highest point MP1 lies on the center line LC in the R1 region of the first arc R1. That is, the first height h1 is a height of the inner plate 10 on the center line LC. In the present embodiment, the highest point MP2 lies on the lines La and Lb, which pass through the centers Oa and Ob of the pin holes 15a and 15b and are orthogonal to the division line PL. An arc segment of the outer plate 15 that includes the highest point MP2 and the area surrounding the highest point MP2 is the second sliding contact area S2, as described above.The positions of the highest points MP1 and MP2 are not limited to those of the present embodiment. The highest point MP1 can be located at a position shifted from the center line LC in the direction of the division line PL. The highest points MP2 can be located at positions shifted from lines La and Lb in the direction of the division line PL.

[0025] The first height h1 and the second height h2 are defined such that they satisfy the relationship h1 > h2. If the relationship h1 > h2 holds, the first sliding contact area S1 of the inner plate 10 is preferentially in sliding contact with the guide element 4 relative to the outer plate 15. That is, since the inner plate 10 projects from the outer plate 15 by a height difference Δh = h1 - h2, more specifically, since the first sliding contact area S1 is defined as a section of the inner plate 10 that projects in the direction of the shoe 8a with respect to an imaginary line SL connecting the highest points MP2 of the outer plate 15 that are adjacent to each other, the first sliding contact area S1 preferentially comes into contact with a shoe surface of the guide element 4 relative to the second sliding contact area S2.In the present embodiment, since the first sliding contact area S1 is formed within a span shorter than the chain pitch TP, friction with respect to the guide element 4 can be reduced. The height difference Δh, which is the difference between h1 and h2, can be appropriately defined, but can, for example, be set within a range of 0.1 mm to 0.27 mm.

[0026] The timing chain 5 includes a lowered section 18 that stores lubricating oil. Fig. 5 is an enlarged view of a main part of Fig. 4 to describe the lowered section 18. Fig. Figure 5 shows a virtual common tangent line TL connecting an arc forming the first sliding contact area S1 and an arc forming the second sliding contact area S2. The recessed section 18 is defined by the common tangent line TL, an outer contour line of the inner plate 10, and an outer contour line of the outer plate 15 in a side view of the timing chain 5. The recessed section 18 is essentially a V-shaped recessed section with a large opening width, located between the first sliding contact area S1 and the second sliding contact area S2, and has an intersection IN of the outer contour lines of the inner plate 10 and the outer plate 15 as its deepest section.

[0027] The lowered section 18 can be used as an accumulation area for lubricating oil. In the present embodiment, the first sliding contact area S1, which has its highest point above the pitch line PL, is formed in a span that is shorter than the chain pitch TP, and the contact area with the guide element 4 is small. For this reason, the contact surface pressure at a contact section where the first sliding contact area S1 is in contact with the guide element 4 is high, and the oil film thickness of any lubricating oil that is intermediately positioned between the first sliding contact area S1 and the guide element 4 tends to be small.

[0028] In the present embodiment, the recessed section 18, in which lubricating oil can accumulate, is located between the first sliding contact area S1 and the second sliding contact area S2. An oil reservoir created in the recessed section 18 can serve as a supply source of lubricating oil for the first sliding contact area S1. Therefore, oil film breakdown of the timing chain 5 can be prevented, and consequently, wear of the guide element 4 can be suppressed. [Achieving both a reduction in friction and a suppression of wear on a guide]

[0029] According to the timing chain 5 of the present embodiment, it is possible to achieve both a reduction in friction with respect to the guide element 4 and a suppression of wear of the guide element 4. This aspect is illustrated with reference to diagrams (A), (B) and (C) of Fig. 6 described. In an upper diagram (A) of Fig. Figure 6 shows the timing chain 5 and the shoe 8a of the tensioning arm 8, which is one of the guide elements 4. Lower diagrams (B) and (C) of Fig. Figure 6 shows enlarged views of section A1 of the upper diagram (A). The diagram (B) of the lower diagrams is a schematic diagram showing a contact state of the timing chain 5 with respect to the shoe 8a during an initial engagement phase of the timing chain transmission device 1, and the diagram (C) is a schematic view showing the contact state after a progression of wear of the shoe 8a.

[0030] As in Fig. 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 have a relationship h1 > h2. For this reason, during the initial insertion phase, which is shown in diagram (B) of Fig. As shown in Figure 6, the first sliding contact area S1 of the inner plate 10 is preferably in sliding contact with the shoe 8a, which acts as a guide, relative to the second sliding contact area S2 of the outer plate 15. Here, the length in one direction along the pitch line PL of the first sliding contact area S1 is set to 73% to 86% of the chain pitch TP. Therefore, it is possible to achieve both a reduction in friction of the timing chain 5 with respect to the shoe 8a and a suppression of wear on the guide element 4 in a well-balanced manner.

[0031] Although both friction reduction and wear suppression are achieved in a well-balanced manner, the shoe 8a gradually wears down due to sliding contact with the timing chain 5. As shown in diagram (C) of Fig. As shown in Figure 6, a shoe groove 8G, formed by the first sliding contact area S1 of the inner plate 10, is created in the shoe 8a due to wear.

[0032] In the non-slip contact area SN of the inner plate 10, the outer plate 15 has a greater height. Therefore, as wear of the shoe 8a progresses and the shoe groove 8G deepens, the second slip contact area S2 of the outer plate 15 also comes into slip contact with the shoe 8a. That is, as wear progresses, as shown in diagram (C) of Fig. As shown in Figure 6, the first sliding contact area S1 and the second sliding contact area S2 come into sliding contact with the shoe 8a. As a result, a surface pressure against the shoe 8a is distributed by the inner plate 10 and the outer plate 15, and the progression of wear of the shoe 8a and uneven wear can be suppressed.

[0033] Even in a situation where both the inner plate 10 and the outer plate 15 come into contact with the shoe 8a, a shape of the outer plate 15 contributes to a reduction in friction. An upper diagram of Fig. Figure 7 is a side view of a single body of the outer plate 15 and a lower diagram of Fig. Figure 7 is a view showing a sliding contact state between a guide element 40, which has a small radius of curvature, and the timing chain 5. As above with reference to Fig. As described in Figure 3, the outer plate 15 comprises a pair of circular segments 151, which contain the pin holes 15a and 15b, and the recessed section 152, which is a narrowed section between a pair of circular segments 151. The second sliding contact area S2 lies on both sides of the recessed section 152.

[0034] As shown in diagram (C) of Fig.As shown in Figure 6, even if the shoe groove 8G becomes deep enough that the outer plate 15 comes into sliding contact with the shoe 8a, only an arc segment forming the second sliding contact area S2 actually makes contact with the shoe 8a at the outer plate 15. This is because the outer plate 15 does not have an elliptical shape with a bulge on one long side, and the recessed section 152, which is a narrowed section between a pair of the second sliding contact sections S2, is present. Since the outer plate 15 has a narrowed shape, even in a case where the timing chain 5 is guided by the guide element 40, which has a small radius of curvature, the recessed section 152 does not become a sliding contact section, and only an arc segment of the second sliding contact section S2 actually comes into sliding contact.Furthermore, the second sliding contact area S2 is formed in an arc shape, with the highest point MP2 of the outer plate as its apex. Therefore, even in a situation where not only the inner plate 10 but also the outer plate 15 comes into sliding contact with a guide element due to progressive wear, an increase in friction can be suppressed.

[0035] According to the present embodiment, since the aforementioned function is achieved, it is possible to provide the control chain 5, which can achieve both a reduction of friction with respect to the guide element 4, which includes the shoe 8a, and a suppression of wear of the guide element 4, and which has excellent running stability over a long period of time. In particular, if a length in one direction along the pitch line PL of the first sliding contact area S1 is set to a length of 73% to 86% of the chain pitch TP, a suppression of surface pressure applied to the guide element 4 by the first sliding contact area S1 and a suppression of friction with respect to the guide element 4 can be achieved more advantageously.

[0036] The embodiment described above comprises an invention shown below.

[0037] A chain according to one aspect of the present invention is a chain comprising a plurality of outer links, each comprising a pair of outer plates and a pair of pins connecting the pair of outer plates, and a plurality of inner links, each comprising 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, wherein the inner plate comprises a rear surface having a first sliding contact area, which comes into sliding contact with a guide that guides the chain when the chain is driven, and a non-sliding contact area, which does not come into sliding contact with the guide, the first sliding contact area being formed in a span shorter than one chain pitch, by a plurality of arcs curving in the same direction.In the first sliding contact area, the inner plate has a height greater than the height of the outer plate with respect to a division line connecting the centers of a pair of pin holes open in the outer plate through which the pair of pins passes; in the non-sliding contact area, the outer plate has a height greater than the height of the inner plate with respect to a height of the division line; and if a height from the division line to a highest point of the inner plate in the first sliding contact area is defined as a first height h1, and a height from the division line to a highest point of the outer plate in the non-sliding contact area is defined as a second height h2, then the relationship h1 > h2 is satisfied.

[0038] From this perspective, since the relationship h1 > h2 holds, the first sliding contact area of ​​the inner plate is preferentially in sliding contact with the guide relative to the outer plate. Since this first sliding contact area spans a distance shorter than one chain pitch, friction with respect to the chain guide can be reduced. However, wear of the guide due to sliding contact is unavoidable. Here, because the outer plate has a greater height in the non-sliding contact area of ​​the inner plate, the outer plate can also come into sliding contact with the guide, depending on changes in the chain's running condition. Therefore, the surface pressure on the guide is distributed by the inner and outer plates, and it is possible to suppress the progression of guide wear and uneven wear.Therefore, it is possible to provide a chain that can achieve both a reduction in friction with respect to the chain guide and a suppression of wear on the chain guide, and has excellent running stability over a long period of time.

[0039] In the above chain, the first sliding contact area preferably has a length of 73% to 86% of the chain pitch with a length in one direction along the pitch line.

[0040] From this point of view, since the length with respect to the chain pitch of the first sliding contact area is fixed within the aforementioned range, it is possible to achieve a more advantageous suppression of surface pressure applied to the guide by the first sliding contact area and a suppression of friction with respect to the guide of the first sliding contact area.

[0041] In the above chain, the first sliding contact area preferably comprises a first arc extending on both sides over a center line extending in a direction orthogonal to the dividing line of the inner plate, and a pair of second arcs extending outwards from both ends of the first arc, and the first height is preferably a height at the center line.

[0042] In particular, the radius of the first arc is preferably larger than the radius of the second arc, and the length occupied by the first arc in the first sliding contact area is preferably a length of 5% to 48% of the total length of the first sliding contact area in one direction along the division line.

[0043] Reducing friction on the guide and suppressing wear on the guide are inherently conflicting goals. From the perspective outlined above, it is possible to achieve a well-balanced approach to both friction reduction and wear suppression.

[0044] In the above chain, there is an area comprising a section of the second height h2 at the outer plate, preferably a second sliding contact area comprising an arc that can be brought into sliding contact with the guide.

[0045] From this perspective, even if a condition arises where the second sliding contact area of ​​the outer plate comes into contact with the guide due to chain movement or similar factors, friction against the guide can be suppressed because the second sliding contact area has an arc-like shape. Furthermore, since the second sliding contact area, together with the first sliding contact area of ​​the inner plate, comes into sliding contact with the guide, it is possible to contribute to suppressing surface pressure on the guide and thus reducing wear on the guide.

[0046] In the aforementioned chain, a lowered section is preferably provided in a side view of the chain, defined by a common tangent line connecting an arc forming the first sliding contact area and an arc forming the second sliding contact area, an outer contour line of the inner plate and an outer contour line of the outer plate.

[0047] From this perspective, the lowered section can be used as an accumulation area for lubricating oil. Therefore, oil film breakdown in the chain can be suppressed, and consequently, wear on the guide can be reduced.

[0048] In the above chain, the difference between the first height h1 and the second height h2 is preferably in a range of 0.1 mm to 0.27 mm.

[0049] From this perspective, surface pressure on the chain guide can be further suppressed. In a case where a groove in the guide is formed by wear due to sliding contact of the first sliding contact area, the second sliding contact area also comes into sliding contact with the guide. By setting a difference between h1 and h2 within the aforementioned numerical range, the point in time at which both the first and second sliding contact areas come into sliding contact with the guide can be optimized, and further wear of the guide can be suppressed. Therefore, stable chain operation can be maintained.

[0050] In the chain described above, the outer plate preferably has a recessed section that is recessed in the direction of the division line in a central area in one direction along the division line, and the second sliding contact area is preferably arranged at both end sections of the recessed section.

[0051] From this perspective, the outer plate has a shape that includes a recessed section between a pair of the secondary sliding contact areas. Because of this, it is less likely that any area of ​​the outer plate other than the secondary sliding contact area will come into sliding contact with the guide. Therefore, even in cases where the guide has a relatively small radius of curvature, it is less likely that a central area of ​​the outer plate will come into sliding contact with the guide. Consequently, friction with respect to the guide is reduced in a straightforward manner.

[0052] According to the present invention, it is possible to provide a chain that is capable of both reducing friction with respect to a chain guide and suppressing wear of the chain guide.

[0053] This application is based on Japanese patent application No. 2024-169378, which was filed with the Japanese Patent Office on September 27, 2024, the contents of which are incorporated herein by reference.

[0054] Although the present invention has been fully described by means of an example with reference to the accompanying drawings, it is understood that various modifications and variations will be apparent to those skilled in the art. Therefore, unless otherwise stated, such modifications and variations shall be interpreted as being included within the scope of the present invention as defined below. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 5259775 [0002, 0003]

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