Chain

Abstract

Provided is a chain in which inner links and outer links are alternately connected. An inner link plate in the inner link has a first sliding contact region in sliding contact with the guide and a non-sliding contact region not in sliding contact with the guide. The first sliding contact region is formed in a range shorter than the chain pitch. In the first sliding contact region, the height of the inner link plate from the pitch line is greater than the height of the outer link plate from the pitch line. In the non-sliding contact area, the height of the outer link plate from the pitch line is greater than the height of the inner link plate from the pitch line. When the height from the pitch line to the highest point of the inner link plate in the first sliding contact region is set as a first height (h1), and the height from the pitch line to the highest point of the outer link plate in the non-sliding contact region is set as a second height (h2), the relationship h1 > h2 is satisfied. Accordingly, friction with the chain guide can be reduced, and abrasion of the chain guide can be restrained.

Description

TECHNICAL FIELD

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

[0002] A chain for power transmission is known, which is alternately connected by an outer link and an inner link connected by a pin inserted through a bushing, wherein the outer link is connected by a pair of outer link plates by the pin, and the inner link is connected by a pair of inner link plates by a bushing. A chain is disclosed in Japanese Patent Publication No. 5259775, in which a sliding contact arc region that is in sliding contact with a chain guide (for example, a chain rail) is provided on the back surface of the inner link plate, thereby reducing the frictional loss with the chain guide.

[0003] In the chain of Japanese Patent Publication No. 5259775, the sliding contact arc region is set to be longer than the chain pitch. However, if the length of the sliding contact region of the chain with the chain guide is long, the friction cannot be sufficiently reduced at times. On the other hand, if the length of the sliding contact region is shortened, the surface pressure of the chain applied to the chain guide becomes high, and the sliding surface of the chain guide is sometimes accelerated in wear. SUMMARY

[0004] An object of the present application is to provide a chain that can reduce the friction with a chain guide and can suppress the wear of the chain guide.

[0005] An aspect of the present application relates to a chain including: a plurality of outer links each having a pair of outer link plates and a pair of pin shafts connecting the pair of outer link plates; and a plurality of inner links each having a pair of inner link plates and a pair of sleeves connecting the pair of inner link plates, wherein the outer links and the inner links are alternately connected by the pin shafts being inserted through the sleeves, thereby forming the chain, the inner link plate includes a back surface having a first sliding contact region that is in sliding contact with a guide member that guides the chain when the chain is driven, and a non-sliding contact region that is not in sliding contact with the guide member, the first sliding contact region includes a plurality of circular arcs having the same protruding direction, and is formed in a range shorter than a chain pitch, a height of the inner link plate from a pitch line is greater than a height of the outer link plate from the pitch line in the first sliding contact region, the pitch line is a line connecting centers of a pair of pin holes provided in the outer link plate for the pair of pin shafts to be inserted, a height of the outer link plate from the pitch line is greater than a height of the inner link plate from the pitch line in the non-sliding contact region, when a height of the inner link plate from the pitch line to an apex in the first sliding contact region is set as a first height h1, and a height of the outer link plate from the pitch line to the apex in the non-sliding contact region is set as a second height h2, a relationship of h1 > h2 is satisfied.

[0006] According to the present application, it is possible to reduce friction with a chain guide member, and to suppress wear of the chain guide member. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a front view showing an example of a timing chain transmission device.

[0008] Figure 2 is a partial cutaway plan view of a timing chain of an embodiment of the chain to which the present application relates.

[0009] Figure 3 is Figure 2 is a side view of the timing chain shown in

[0010] Figure 4 is a main part enlarged view of Figure 3 with the first height h1 and the second height h2 additionally noted.

[0011] Figure 5 is a main part enlarged view of Figure 4 with a recess for storing oil.

[0012] Figure 6 is a schematic view for explaining a contact condition of the timing chain of the embodiment and a foot member.

[0013] Figure 7is a schematic view of the contact state of the timing chain and the guide member of the present embodiment. DETAILED DESCRIPTION

[0014] Hereinafter, an embodiment of the present application will be described in detail based on the drawings. The chain to which the present application is applied is a chain for power transmission that can be assembled in a power transmission mechanism of a mobile vehicle such as a four-wheeled or two-wheeled vehicle, or a heavy machine or an industrial machine. In the following embodiment, as one example of the chain to which the present application is applied, a timing chain of an engine of an internal combustion engine is exemplified.

[0015] [Structure of Timing Chain Drive]

[0016] Figure 1 is a front view showing one example of a timing chain drive 1. The timing chain drive 1 is assembled, for example, in an engine of an automobile. The engine is a power source for running drive of the automobile, and includes a cylinder and a piston, a crankshaft 2, and a pair of camshafts 3, which are not shown in the drawing. The crankshaft 2 is connected to the piston, and is rotationally driven around the shaft in accordance with the reciprocating motion of the piston in the cylinder. The two camshafts 3 respectively perform opening and closing drive of an intake valve and an exhaust valve attached to the cylinder. The camshafts 3 are rotationally linked with the crankshaft 2.

[0017] The timing chain drive 1 includes a crankshaft sprocket 2a, a pair of camshaft sprockets 3a, a guide member 4, and a timing chain 5. The crankshaft sprocket 2a is installed at the shaft end of the crankshaft 2, and is integrally rotated with the crankshaft 2. The pair of camshaft sprockets 3a are respectively installed at the shaft ends of the pair of camshafts 3, and are integrally rotated with the camshafts 3. The timing chain 5 is fitted between the crankshaft sprocket 2a and the pair of camshaft sprockets 3a. The timing chain 5 transmits the power of the crankshaft 2 to the camshafts 3. That is, based on the rotation of the crankshaft sprocket 2a, the timing chain 5 is circumferentially rotated, and in conjunction therewith, the camshaft sprockets 3a are driven to rotate, so that the power of the crankshaft 2 is transmitted to the camshafts 3.

[0018] The guide member 4 is disposed at the outer periphery of the timing chain 5, and functions as a guide rail that guides the circumferential rotation of the timing chain 5. The guide member 4 includes a first chain guide rail 6, a second chain guide rail 7, and a tension arm 8. By the outer peripheral side of the timing chain 5 being in sliding contact with each member of the guide member 4, the rocking of the timing chain 5 is suppressed, and stable circumferential rotation is ensured.

[0019] As Figure 1In the case where the timing chain 5 is circumferentially rotated in the clockwise direction as indicated by the arrow, the sprocket 2a of the crankshaft and the sprocket 3a of the camshaft on the left side become slack sides of the timing chain 5, and the remaining portions become tension sides by being applied with the driving load of the camshaft 3. The chain guides 6, 7 are arranged on the tension sides, and the tension arm 8 is arranged on the slack side. The chain guides 6, 7 are fixed to the engine block. The tension arm 8 is a member that applies tension to the timing chain 5, and includes a shoe 8a and a fulcrum 8b. The shoe 8a is in sliding contact with the timing chain 5. The fulcrum 8b is attached to the engine block to swingably support the one end side of the tension arm 8. The plunger of the chain tensioner 9 abuts the other end side of the tension arm 8. The timing chain 5 is applied with appropriate tension from the chain tensioner 9 via the tension arm 8.

[0020] [Overall structure of timing chain]

[0021] The overall structure of the timing chain 5 will be described. Figure 2 is a partial cutaway plan view of the timing chain 5, Figure 3 is a side view of the timing chain 5. The timing chain 5 is a ring-shaped structure body in which a plurality of inner links 13 and a plurality of outer links 17 are alternately connected. The inner link 13 includes a pair of inner link plates 10, a pair of sleeves 11, and a pair of rollers 12. The outer link 17 includes a pair of outer link plates 15 and a pair of pin shafts 16. In addition, in Figure 3 is shown a side view of a state in which one of the outer link plates 15 and the sleeve 11 and the pin shaft 16 on one side are removed. Further, when viewed from the side, actually, most of the inner link plate 10 is covered with the outer link plate 15 and cannot be seen, and in Figure 3 , for the sake of explanation, it is shown as if it is seen. The inner link plate 10 is shown in thick lines, and the outer link plate 15 is shown in thin lines.

[0022] When viewed from the side, the pair of inner link plates 10 each have a substantially elliptical shape, and are arranged in parallel. The first sleeve hole 10a is passed through at one end side in the length direction of the inner link plate 10, and the second sleeve hole 10b is passed through at the other end side. The both ends of the pair of sleeves 11 are respectively pressed into the sleeve holes 10a, 10b, so that the pair of inner link plates 10 are connected. The sleeve 11 has a through hole 11a for the pin shaft 16 to pass through. The roller 12 is freely rotatably fitted to the sleeve 11 between the pair of inner link plates 10.

[0023] When viewed from the side, the pair of outer links 15 each have a lengthwise central depression in a shape similar to the numeral "8" and are arranged in parallel with the inner links 13 sandwiched therebetween. At one end side in the lengthwise direction of the outer links 15, a first pin hole 15a is bored, and at the other end side, a second pin hole 15b is bored. The pair of pins 16 are press-fitted into the pin holes 15a, 15b and are fixed by riveting, whereby the pair of outer links 15 are connected. The pins 16 are inserted through the through holes 11a with both end portions fixed to the pin holes 15a, 15b. The inner links 13 and the outer links 17 are alternately connected by the pins 16 inserted through the through holes 11a.

[0024] [Detailed structure of timing chain]

[0025] The structure of the timing chain 5 will be described in further detail with reference to a main part enlarged view of Figure 3 Figure 4 When the center of the first pin hole 15a bored in the outer link 15 is denoted as Oa and the center of the second pin hole 15b is denoted as Ob, the pitch line PL is a line connecting the centers Oa, Ob. Further, the lengthwise direction of the inner link 10 and the outer link 15 is a direction in which the pitch line PL extends. The chain pitch TP of the timing chain 5 is a length between the center Oa and the center Ob described above. Further, in the present embodiment, a case where the shape is symmetrical with the pitch line PL as the axis of symmetry is described, but the shape need not be symmetrical.

[0026] The peripheral surface of the inner link 10 located on the outer peripheral side with respect to the pitch line PL in the timing chain 5 is a back surface 10R that is in sliding contact with the guide member 4. The peripheral surface of the inner link 10 located on the inner peripheral side with respect to the pitch line PL in the timing chain 5 is an inner surface 10Q that is not in sliding contact with the guide member 4. The back surface 10R and the inner surface 10Q have a shape symmetrical with the pitch line PL as the center. Further, the inner link 10 has a shape symmetrical left and right with a widthwise center line LC extending in a direction perpendicular to the pitch line PL at a position of 1 / 2 pitch of the chain pitch TP as the axis of symmetry.

[0027] The inner link 10 has a first sliding contact region S1 and a non-sliding contact region SN on the back surface 10R. The first sliding contact region S1 is in sliding contact with 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 region SN is a region that is not in sliding contact with the guide member 4 even when the timing chain 5 is driven. The first sliding contact region S1 is a specified region of the inner link 10 in the lengthwise direction with the center line LC as the center. The non-sliding contact region SN is located on the right and left sides of the first sliding contact region S1.

[0028] ​The first sliding contact region S1 is formed in a range shorter than the chain pitch TP. The range of the first sliding contact region S1 is set so as to reduce the friction with the guide member 4. However, if the length of the first sliding contact region S1 is too short, the surface pressure applied to the guide member 4 becomes high, which may, for example, cause the foot member 8a of the tension arm 8 to be worn out prematurely. That is, there is a trade-off relationship between reducing the friction and suppressing the wear of the guide member. In view of this, it is preferable that the length of the first sliding contact region S1 in the direction along the pitch line PL be set to a length of 73% to 86% of the chain pitch TP. By setting this length, it is possible to achieve a balance between reducing the friction and suppressing the wear.

[0029] The first sliding contact region S1 includes a plurality of circular arcs having the same protruding direction. Specifically, the first sliding contact region S1 includes a first circular arc R1 that passes through the center line LC and extends to both left and right sides with the center line LC as a center, and a pair of second circular arcs R2 that are located at both ends of the first circular arc R1 and extend outward from the both ends, respectively. The first circular arc R1 and the second circular arcs R2 are circular arcs that protrude in a direction away from the pitch line PL, that is, the outer peripheral side. The first circular arc R1 is a circular arc having a larger radius. The radius of the first circular arc R1 is larger than the radius of the second circular arcs R2. In Figure 3 The R1 region formed by the first circular arc R1 and the R2 region formed by the second circular arc R2 on the back surface 10R are shown in FIG. 8.

[0030] The R1 region is located near the center line LC. The R2 region on the right side of the R1 region extends from the right end of the R1 region to a position beyond a line La that passes through the center Oa of the first pin shaft hole 15a and is perpendicular to the pitch line PL. A third circular arc R3 formed by a circular arc concentric with the sleeve hole 10a is continuously provided at the right end of this R2 region. The R2 region on the left side of the R1 region extends from the left end of the R1 region to a position beyond a line Lb that passes through the center Ob of the second pin shaft hole 15b and is perpendicular to the pitch line PL. A left third circular arc R3 is continuously provided at the left end of this R2 region. For example, the radius of the first circular arc R1 is 100 mm, the radius of the second circular arc R2 is 20 mm, and the radius of the third circular arc is 3.5 mm.

[0031] The first sliding contact region S1 includes a first circular arc R1 and a portion of two second circular arcs R2. Preferably, the length of the portion of the first circular arc R1 in the first sliding contact region S1 in the direction along the pitch line PL is 5 to 48% of the entire length of the first sliding contact region S1. By configuring the first circular arc R1 having a large radius, that is, having a small degree of bending, to have a length in the above range, the reduction of friction and the suppression of wear can be achieved in a balanced manner. The first sliding contact region S1 can be formed by continuously providing a plurality of circular arcs that protrude in a direction away from the pitch line PL, or can be formed by continuously providing three or more circular arcs. In addition, a portion of the first sliding contact region S1 can include a short linear portion that connects the plurality of circular arcs.

[0032] The outer link plate 15 includes a pair of circular portions 151 located around the pair of pin hole 15a, 15b, and a recessed portion 152 located in a central region between the pair of circular portions 151. The outer link plate 15 has a shape symmetrical with respect to the back surface 10R side and the inner surface 10Q side with the pitch line PL as a reference. In addition, the outer link plate 15 has a shape symmetrical with respect to the left and right sides with a center line extending in a direction perpendicular to the pitch line PL at a position of 1 / 2 pitch of the chain pitch TP as a symmetry axis. The recessed portion 152 is recessed toward the pitch line PL. The outer link plate 15 has the recessed portion 152, thereby having a profile shape in which the central region in the direction of the pitch line PL is tapered.

[0033] The outer link plate 15 includes, at both end portions of the recessed portion 152, a second sliding contact region S2 that can be in sliding contact with the guide member 4. The second sliding contact region S2 includes a portion of a plurality of circular arcs that constitute the circular portion 151. The portion of the plurality of circular arcs is a circular arc portion that is adjacent to the recessed portion 152. As shown in FIG. 6, in a side view, the second sliding contact region S2 is located in a region corresponding to the non-sliding contact region SN of the inner link plate 10, and is located on both sides of the first sliding contact region S1. Figure 3

[0034] Also, referring to a close-up view of a main portion of the outer link plate 15 as Figure 3 Figure 4 , the height relationship from the pitch line PL of the first sliding contact region S1 and the second sliding contact region S2 will be described. In the first sliding contact region S1, the height of the inner link plate 10 is greater than the height of the outer link plate 15 in terms of the height from the pitch line PL. On the other hand, in the non-sliding contact region SN, the height of the outer link plate 15 is greater than the height of the inner link plate 10 in terms of the height from the pitch line PL.

[0035] ​​The height of the inner link plate 10 in the first sliding contact region S1 from the pitch line PL to the highest point MP1 is set to a first height h1. The height of the outer link plate 15 in the non-sliding contact region SN from the pitch line PL to the highest point MP2 is set to a second height h2. In the present embodiment, the highest point MP1 is located in the R1 region of the first circular arc R1 and on the center line LC. That is, the first height h1 is the height of the inner link plate 10 on the center line LC. In the present embodiment, the highest point MP2 is located on the lines La, Lb passing through the centers Oa, Ob of the pin shaft holes 15a, 15b and perpendicular to the pitch line PL. The circular arc portion of the outer link plate 15 including the highest point MP2 and its vicinity becomes the above-described second sliding contact region S2. The positions of the highest points MP1, MP2 are not limited to the present embodiment. The highest points MP1, MP2 can also be present at positions displaced from the center line LC and from the lines La, Lb in the direction of the pitch line PL.

[0036] The first height h1 and the second height h2 are set in a manner satisfying the relationship h1 > h2. If the relationship h1 > h2 is satisfied, the first sliding contact region S1 of the inner link plate 10 comes into sliding contact with the guide member 4 before the outer link plate 15. That is, since the inner link plate 10 protrudes higher than the outer link plate 15 by the height difference Ah = h1 - h2, and more specifically, the portion of the inner link plate 10 protruding to the side of the foot member 8a with respect to the virtual line SL connecting the highest points MP2 of the adjacent outer link plates 15 is defined as the first sliding contact region S1, the first sliding contact region S1 comes into contact with the foot member surface of the guide member 4 before the second sliding contact region S2. In the present embodiment, the first sliding contact region S1 is formed in a range shorter than the chain pitch TP, and thus it is possible to reduce the friction with the guide member 4. The difference between h1 and h2, that is, the height difference Ah can be appropriately set, for example, in the range of 0.1 mm to 0.27 mm.

[0037] The timing chain 5 includes a recess 18 that stores lubricating oil. Figure 5 is a main part enlarged view for explaining the recess 18. Figure 4 is a main part enlarged view for explaining the recess 18. Figure 5 A virtual common tangent line TL that contacts (just touches) the circular arc constituting the first sliding contact region S1 and contacts (just touches) the circular arc constituting the second sliding contact region S2 is shown in FIG. 6. When the timing chain 5 is viewed from the side, the recess 18 is demarcated by the above-described common tangent line TL, the outer shape contour line of the inner link plate 10, and the outer shape contour line of the outer link plate 15. The recess 18 is a large approximately V-shaped recess having a large opening width between the first sliding contact region S1 and the second sliding contact region S2 and having the intersection IN of the outer shape contour line of the inner link plate 10 and the outer shape contour line of the outer link plate 15 as the deepest portion.

[0038] The recess 18 can be utilized as a lubricating oil retention area. In this embodiment, the first sliding contact area S1, which has the highest height from the pitch line PL, is formed in a range shorter than the chain pitch TP, thereby reducing the contact area with the guide member 4. Therefore, the contact surface pressure at the contact point where the first sliding contact area S1 contacts the guide member 4 becomes higher, and the thickness of the lubricating oil film between them tends to become thinner. In this embodiment, a recess 18 exists between the first sliding contact area S1 and the second sliding contact area S2, allowing lubricating oil to remain. The oil accumulated in this recess 18 can be used as a lubricating oil supply source to the first sliding contact area S1. Therefore, oil film breakdown of the timing chain 5 can be suppressed, and consequently, wear of the guide member 4 can be suppressed.

[0039] [Regarding reducing friction and suppressing guide rail wear]

[0040] According to this embodiment, the timing chain 5 can reduce friction with the guide member 4 and suppress wear on the guide member 4. (See reference...) Figure 6 Explain this point. Figure 6 The figure above (A) shows the timing chain 5 and the foot 8a of the tension arm 8, which is one of the guide members 4. Figure 6 Figures (B) and (C) below are enlarged views of part A1 of Figure (A) above. Figure (B) below is a schematic diagram showing the contact between the timing chain 5 and the foot piece 8a in the initial stage of use of the timing chain drive device 1, and Figure (C) is a schematic diagram showing the contact after the wear of the foot piece 8a has progressed.

[0041] like Figure 4 As shown, the first height h1 of the first sliding contact area S1 and the second height h2 of the second sliding contact area S2 are related as h1 > h2. Therefore, in Figure 6 As shown in Figure (B) during the initial stage of use, the first sliding contact area S1 of the inner chain plate 10 makes sliding contact with the foot member 8a, which serves as a guide rail, before the second sliding contact area S2 of the outer chain plate 15. Here, the length of the first sliding contact area S1 in the direction along the pitch line PL is set to 73% to 86% of the chain pitch TP. Therefore, it is possible to evenly reduce the friction between the timing chain 5 and the foot member 8a and suppress the wear of the guide member 4.

[0042] Although it can achieve a balanced reduction in friction and suppression of wear, the timing chain 5's sliding contact will gradually cause the foot 8a to wear. For example... Figure 6 As shown in Figure (C), due to the wear, a shoe groove 8G will be generated on the shoe 8a, which will be cut off by the first sliding contact area S1 of the inner chain plate 10.

[0043] In the non-sliding contact area SN of the inner link plate 10, the height of the outer link plate 15 is greater than the height of the inner link plate 10. Therefore, if the wear of the foot 8a progresses and the foot groove 8G deepens, the second sliding contact area S2 of the outer link plate 15 will also slide against the foot 8a. That is, if... Figure 6 As shown in Figure (C), the wear progresses as indicated, and the first sliding contact area S1 and the second sliding contact area S2 slide in contact with the foot member 8a. As a result, the surface pressure on the foot member 8a is dispersed by the inner chain plate 10 and the outer chain plate 15, thereby suppressing the wear progression of the foot member 8a and the unevenness of wear.

[0044] Even when the inner link plate 10 and the outer link plate 15 are in contact with the foot member 8a, the shape of the outer link plate 15 helps to reduce friction. Figure 7 The image above is a side view of the outer chain plate 15 unit. Figure 7 The following diagram illustrates the sliding contact state between the guide member 40 with a small radius of curvature and the timing chain 5. Based on Figure 3 As described above, the outer chain plate 15 includes: a pair of circular portions 151 having pin holes 15a and 15b; and a tapering portion, i.e., a recess 152, between the pair of circular portions 151. The second sliding contact area S2 is located on both sides of the recess 152.

[0045] like Figure 6 As shown in Figure (C), even if the foot groove 8G deepens to the point where the outer chain plate 15 slides into contact with the foot 8a, only the arcuate portion forming the second sliding contact area S2 of the outer chain plate 15 actually contacts the foot 8a. This is because the outer chain plate 15 is not an elliptical shape with protruding long sides, but rather has a tapered recess 152 between a pair of second sliding contact areas S2. Due to the tapered shape of the outer chain plate 15, even when the timing chain 5 is guided by the guide member 40 with a small radius of curvature, the recess 152 does not become a sliding contact portion; in fact, only the arcuate portion of the second sliding contact area S2 slides into contact. Moreover, the second sliding contact area S2 is formed as an arcuate shape with the highest point MP2 of the outer chain plate as its apex. Therefore, even when both the inner chain plate 10 and the outer chain plate 15 slide into contact with the guide member due to wear progression, the increase in friction can be suppressed.

[0046] According to the present embodiment, since the above-described effects are provided, it is possible to provide a timing chain 5 that can reduce friction with the guide member 4 including the foot 8a and can suppress wear of the guide member 4, and that has excellent traveling stability for a long period of time. In particular, if the length of the first sliding contact region 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 more favorably suppress the surface pressure applied to the guide member 4 by the first sliding contact region S1, and to suppress friction with the guide member 4.

[0047] The embodiment described above includes the invention shown below.

[0048] One aspect of the present invention relates to a chain, comprising: a plurality of outer links each having a pair of outer link plates and a pair of pin shafts connecting the pair of outer link plates; and a plurality of inner links each having a pair of inner link plates and a pair of sleeves connecting the pair of inner link plates, wherein the outer links and the inner links are alternately connected by the pin shafts being inserted through the sleeves, thereby forming the chain, the inner link plates include a back surface having a first sliding contact region that is in sliding contact with a guide member that guides the chain when the chain is driven, and a non-sliding contact region that is not in sliding contact with the guide member, the first sliding contact region includes a plurality of circular arcs having the same protruding direction, and is formed in a range shorter than a chain pitch, in the first sliding contact region, a height of the inner link plate from a pitch line is greater than a height of the outer link plate from the pitch line, the pitch line is a line connecting centers of a pair of pin holes each provided in the outer link plate for the pin shafts to be inserted, in the non-sliding contact region, the height of the outer link plate from the pitch line is greater than the height of the inner link plate from the pitch line, when a height of the inner link plate from the pitch line to an apex in the first sliding contact region is set as a first height h1, and a height of the outer link plate from the pitch line to the apex in the non-sliding contact region is set as a second height h2, a relationship of h1 > h2 is satisfied.

[0049] According to the technical solution, since h1 > h2, the first sliding contact area of the inner link plate first makes sliding contact with the guide rail. Since the first sliding contact area is formed in a range shorter than the chain pitch, friction with the chain guide rail can be reduced. On the other hand, guide rail wear caused by the sliding contact is inevitable. Here, since the height of the outer link plate is greater in the non-sliding contact area of the inner link plate, the outer link plate can also make sliding contact with the guide rail depending on the running condition of the chain. Therefore, the surface pressure on the guide rail is dispersed by the inner link plate and the outer link plate, thereby inhibiting the progress of wear of the guide rail and uneven wear. Thus, a chain that can reduce friction with the chain guide rail and inhibit wear of the chain guide rail, and has excellent running stability in the long term can be provided.

[0050] In the chain described above, it is preferable that the length of the first sliding contact area in the direction along the pitch line be 73% to 86% of the chain pitch.

[0051] According to the technical solution, since the length of the first sliding contact area with respect to the chain pitch is set in the range described above, the surface pressure applied to the guide rail by the first sliding contact area can be more effectively inhibited, and friction between the first sliding contact area and the guide rail can be inhibited.

[0052] In the chain described above, it is preferable that the plurality of circular arcs include a first circular arc that passes through a center line of the inner link plate extending in a direction perpendicular to the pitch line and extends to both sides of the pitch line with the center line as the center, and a pair of second circular arcs that extend outward from both ends of the first circular arc, respectively, and the first height be the height at the center line.

[0053] It is particularly preferable that the radius of the first circular arc be greater than the radius of the second circular arc, and that the length of the portion of the first circular arc in the first sliding contact area in the direction along the pitch line be 5% to 48% of the entire length of the first sliding contact area.

[0054] Reducing friction with the guide rail and inhibiting wear of the guide rail should be opposite issues. According to the technical solution described above, the reduction of friction and the inhibition of wear can be achieved in balance.

[0055] In the chain described above, it is preferable that the area of the portion of the outer link plate including the second height be a second sliding contact area, and that the second sliding contact area include a circular arc that can make sliding contact with the guide member.

[0056] According to the technical solution, even if the second sliding contact region of the outer chain plate contacts the guide rail according to the running state of the chain and the like, since the second sliding contact region is a shape including a circular arc, friction with the guide rail can be suppressed. In addition, the second sliding contact region is in sliding contact with the guide rail together with the first sliding contact region of the inner chain plate, so surface pressure on the guide rail can be suppressed, and wear of the guide rail can be suppressed.

[0057] In the chain described above, preferably further comprising: a recess portion, when the chain is viewed in side view, the recess portion is delimited by a common tangent line, an outer contour line of the inner chain plate, and an outer contour line of the outer chain plate, the common tangent line contacts a circular arc constituting the first sliding contact region and contacts a circular arc constituting the second sliding contact region.

[0058] According to the technical solution, the recess portion can be used as a residence area of lubricating oil. Therefore, oil film breakage of the chain can be suppressed, and as a result, wear of the guide rail can be suppressed.

[0059] In the chain described above, preferably: a difference between the first height and the second height is in a range of 0.1 mm to 0.27 mm.

[0060] According to the technical solution, surface pressure of the chain on the guide rail can be further suppressed. In a case where wear occurs on the guide rail due to sliding contact of the first sliding contact region and a groove is formed on the guide rail, the second sliding contact region also comes into sliding contact with the guide rail. By setting a difference between h1 and h2 in the numerical range described above, timing of a state in which sliding contact of the guide rail is transferred to both the first sliding contact region and the second sliding contact region can be optimized, and progression of wear of the guide rail can be suppressed. Therefore, stable running of the chain can be maintained.

[0061] In the chain described above, preferably: the outer chain plate has a recessed portion recessed toward the pitch line in a central region in a direction of the pitch line, and the second sliding contact region is disposed at both end portions of the recessed portion.

[0062] According to the technical solution, the outer chain plate is a shape having a recessed portion between a pair of second sliding contact regions. Therefore, a portion of the outer chain plate other than the second sliding contact regions does not come into sliding contact with the guide rail. Therefore, for example, in a case where the radius of curvature of the guide rail is relatively small, the central region of the outer chain plate is also less likely to come into sliding contact with the guide rail. Therefore, friction with the guide rail can be easily reduced.

[0063] According to the present application, a chain capable of reducing friction with a chain guide rail and suppressing wear of the chain guide rail can be provided.

[0064] This application is based on Japanese Patent Application No. 2024-169378 filed on September 27, 2024, the content of which is incorporated herein by reference.

[0065] For the purpose of describing the present application, the present application has been adequately and sufficiently described above with reference to the drawings and by way of embodiments, but it should be understood that the described embodiments can be easily changed and / or modified by those skilled in the art. Therefore, the modified or modified embodiments implemented by those skilled in the art can be interpreted as being included in the scope of protection of the claims as long as they are within the level of the claims recited in the claims.

Claims

1. A chain characterized in that Comprising: a plurality of outer links each having a pair of outer link plates and a pair of pin shafts connecting the pair of outer link plates; and a plurality of inner links each having a pair of inner link plates and a pair of sleeves connecting the pair of inner link plates, wherein the outer links and the inner links are alternately connected by the pin shafts inserted through the sleeves, thereby forming the chain, the inner link plate includes a back surface, the back surface has a first sliding contact area that is in sliding contact with a guide member that guides the chain when the chain is driven, and a non-sliding contact area that is not in sliding contact with the guide member, the first sliding contact area includes a plurality of circular arcs having the same convex direction and is formed in a range shorter than a chain pitch, in the first sliding contact area, a height of the inner link plate from a pitch line is greater than a height of the outer link plate from the pitch line, the pitch line being a line connecting centers of a pair of pin holes provided in the outer link plate for insertion of the pair of pin shafts, in the non-sliding contact area, the height of the outer link plate from the pitch line is greater than the height of the inner link plate from the pitch line, when a height of the inner link plate from the pitch line to an apex in the first sliding contact area is set as a first height h1 and a height of the outer link plate from the pitch line to an apex in the non-sliding contact area is set as a second height h2, a relationship h1 > h2 is satisfied.

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

3. The chain according to claim 1, wherein the plurality of circular arcs include a first circular arc that passes through a center line of the inner link plate extending in a direction perpendicular to the pitch line and extends to both sides of the pitch line with the center line as a center, and a pair of second circular arcs that extend outward from both ends of the first circular arc, respectively, the first height is a height on the center line.

4. The chain according to claim 3, wherein a radius of the first circular arc is greater than a radius of the second circular arc, in the first sliding contact area, a length of a portion of the first circular arc in a direction along the pitch line is 5% to 48% of a total length of the first sliding contact area.

5. The chain according to any one of claims 1 to 4, wherein an area of the outer link plate in which the second height is included is a second sliding contact area, and the second sliding contact area includes a circular arc that can be in sliding contact with the guide member. Further comprising:

6. The chain of claim 5 wherein a recessed portion that is demarcated by a common tangent line, an outer contour line of the inner link plate, and an outer contour line of the outer link plate when the chain is viewed from the side, the common tangent line contacting a circular arc that constitutes the first sliding contact area and contacting a circular arc that constitutes the second sliding contact area.

7. The chain according to any one of claims 1 to 4, wherein a difference between the first height and the second height is in a range of v.1 mm to 0.27 mm. ​ 8. The chain according to claim 5, wherein the outer link plate has a recessed portion recessed toward the pitch line in a central region in the direction of the pitch line, and the second sliding contact region is provided at both end portions of the recessed portion.

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