Offset plate and coupling link

Abstract

To provide an offset plate that can suppress premature fracture. [Solution] The offset plate 3 comprises an outer plate portion 31 having a pin hole 34 into which a pin 41 is press-fitted, an inner plate portion 32 having a bushing hole 35 into which a bushing 42 is press-fitted, and an offset portion 33 that connects the outer plate portion 31 and the inner plate portion 32 offset in the axial direction AX. Viewed from the axial direction AX, the contour line of the offset plate 3 has a pair of parallel line portions 301 that extend parallel to the pitch line PL, which connects the center Oa of the pin hole 34 and the center Ob of the bushing hole 45, with the pitch line PL in between. The pair of parallel line portions 301 extend through the offset portion 33 to a section that includes at least a part of the outer plate portion 31 and the inner plate portion 32.

Description

Technical Field

[0001] The present invention relates to an offset plate used for a joint link that connects both ends of a linear chain to form an endless chain, and a joint link.

Background Art

[0002] An endless power transmission chain is known in which an outer link in which a pair of outer plates are connected by pins and an inner link in which a pair of inner plates are connected by bushes are alternately connected by inserting the pins into the bushes. The endless chain is manufactured by connecting both ends of a linear chain with a joint link. Patent Document 1 discloses an example of a joint link using an offset plate. The offset plate includes an outer plate portion having a pin hole, an inner plate portion having a bush hole, and an offset portion that connects the inner and outer plates with an offset.

Prior Art Documents

Patent Documents

[0003]

Patent Document Ⅰ

Summary of the Invention

Problems to be Solved by the Invention

[0004] When tension is applied to the chain during driving, tensile forces act on the outer plate portion and the inner plate portion of the offset plate. As a result, stress concentrates on the offset portion that connects the inner and outer plates. At the same time, a bending force that bends the outer plate portion inward also acts. Due to the action of these forces, the offset plate may break at an early stage of operation in the offset portion or its vicinity.

[0005] An object of the present invention is to provide an offset plate capable of suppressing early breakage and a joint link of a chain using the offset plate. [Means for solving the problem]

[0006] An offset plate according to one aspect of the present invention is an offset plate used in a connecting link that connects both ends of a linear chain to form an endless chain, comprising: an outer plate portion having a pin hole into which a pin is press-fitted; an inner plate portion having a bushing hole into which a bushing is press-fitted; and an offset portion that connects the outer plate portion and the inner plate portion offset in the axial direction of the pin hole and the bushing hole, wherein, when viewed from the axial direction, the contour line of the offset plate has a pair of parallel line portions extending parallel to the pitch line connecting the center of the pin hole and the center of the bushing hole, and the pair of parallel line portions extend through the offset portion to a section that includes at least a part of the outer plate portion and the inner plate portion.

[0007] According to this embodiment, the offset plate has a shape in which a pair of parallel line portions extending parallel to the pitch line extend through the offset portion and into a section including at least a part of the outer plate portion and the inner plate portion. In other words, the offset plate has portions of equal width on either side of the offset portion, comprising the outer plate portion and the inner plate portion. This distributes the stress generated when the chain is driven at the connection point where the outer plate portion and the inner plate portion are connected and in its vicinity, thereby reducing stress. That is, stress concentration at the connection point becomes less likely, and fracture near the offset portion can be suppressed. Consequently, premature fracture of the offset plate can be suppressed.

[0008] In the offset plate described above, the offset plate has a shape in which the direction of extension of the pitch line is the longitudinal direction, and has arc portions at both ends in the longitudinal direction, and it is desirable that the pair of parallel line portions extend over the entire length of the outer plate portion, the offset portion and the inner plate portion, excluding the arc portions.

[0009] In this embodiment, the outer plate portion, the offset portion, and the inner plate portion have the same width along the entire length of the region excluding the arc portions at both ends of the offset plate. Therefore, stress distribution is more easily achieved, and fracture of the offset plate due to stress concentration can be further suppressed.

[0010] In the offset plate described above, the inner plate portion has a first surface facing the direction in which the outer plate portion is offset, and a second surface opposite to the first surface, the bushing hole is a hole that penetrates from the first surface to the second surface, and it is desirable that the inner plate portion has a thickened portion on the second surface that protrudes in the axial direction around the bushing hole.

[0011] According to this embodiment, the rigidity of the offset plate can be increased because it has a thicker section. Therefore, when a tensile force is applied to the offset plate during chain drive, the warping of the offset plate can be suppressed.

[0012] In the offset plate described above, the thickened portion may be an annular projection that protrudes around the bushing hole. According to this embodiment, rigidity can be increased around the entire circumference of the bushing hole.

[0013] In the offset plate described above, the thickened portion may be a plurality of ribs extending radially outward from the periphery of the bushing hole. According to this embodiment, the rigidity near the bushing hole can be increased by installing a plurality of ribs.

[0014] In the offset plate described above, it is preferable that the plurality of ribs include a pair of ribs extending in opposite directions on the pitch line, with the bushing hole in between.

[0015] According to this embodiment, ribs can be provided that can efficiently counteract the warping of the offset plate caused by the tensile force during chain drive.

[0016] In the offset plate described above, the inner plate portion has a first surface facing the direction in which the outer plate portion is offset, and a second surface opposite to the first surface, the bushing hole is a hole that penetrates from the first surface to the second surface, and the inner plate portion may have on the first surface a peripheral wall that forms an annular recess around the bushing hole, a wall portion that rises in the axial direction from the periphery of the bushing hole within the recess, and an annular groove portion formed between the peripheral wall and the wall portion.

[0017] According to this embodiment, the formation of recesses and grooves provides space for a sealing material containing lubricant between the pin and the bushing. Furthermore, forming a wall around the periphery of the bushing hole provides rigidity that helps suppress warping of the inner plate, and also has the advantage of increasing the thickness in the axial direction, thereby ensuring a longer bushing fit width.

[0018] A joint link according to another aspect of the present invention comprises a first offset plate and a second offset plate made of the above-described offset plate, a pin pressed into the pin hole, a first bush pressed into the bush hole and a second bush fitted onto the pin, a first roller fitted onto the first bush and a second roller fitted onto the second bush, and an inner link formed by connecting a pair of inner plates with a connecting member, wherein the first offset plate and the second offset plate are arranged opposite each other with the offset directions of their outer plate portions opposite to each other, one end of the inner link is positioned between the pair of outer plate portions, the pin penetrates the pair of outer plate portions and the inner link, the second bush is part of the connecting member of the inner link, and the second roller is positioned between the pair of inner plates.

[0019] According to this embodiment, stress concentration is less likely to occur at the connection point between the outer plate portion and the inner plate portion of the offset plate, and failure near the offset portion can be suppressed. Therefore, premature failure can be suppressed in an endless chain formed by connecting both ends of a linear chain with the above-mentioned coupling link. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide an offset plate capable of suppressing early breakage, and a joint link of a chain using the offset plate.

Brief Description of the Drawings

[0021] [Figure 1] FIG. 1(A) is a partially broken front view showing a seal chain using a joint link according to an embodiment of the present invention, and FIG. 1(B) is a side view thereof. [Figure 2] FIG. 2 is a partially broken front view of a joint link using an offset plate according to an embodiment of the present invention. [Figure 3] FIGS. 3(A) and 3(B) are perspective views of the offset plate of the present embodiment. [Figure 4] FIG. 4(A) is a side view of the offset plate, FIG. 4(B) is a front view, and FIG. 4(C) is a side view of the other side. [Figure 5] FIG. 5 is a diagram for explaining the warpage generated in the offset plate when a tensile force acts on the joint link. [Figure 6] FIG. 6(A) is a side view of an offset plate according to a comparative example, and FIG. 6(B) is a front view showing the breakage state of a joint link using the offset plate of the comparative example. [Figure 7] FIG. 7 is a perspective view showing an offset plate according to a first modification example. [Figure 8] FIG. 8 is a side view showing an offset plate according to a second modification example.

Mode for Carrying Out the Invention

[0022] Embodiments of the present invention will be described in detail below with reference to the drawings. The offset joint link using the offset plate according to the present invention is used to connect both ends of a linear chain body, which is made up of alternating inner and outer links, to form an endless chain. The offset joint link is used when the total number of inner and outer links constituting the chain body is odd. By applying the offset joint link, fine adjustment of the chain length becomes possible. The chain is a power transmission chain that can be applied to power transmission mechanisms incorporated in, for example, mobile vehicles such as motorcycles or industrial machinery. In the embodiments shown below, a sealed chain is exemplified in which a lubricant is interposed between the pin and bushing connecting the inner and outer links and sealed with a sealing material.

[0023] [Outline of sealed chain configuration] Figure 1(A) is a front view showing a sealed chain 1 using a coupling link according to an embodiment of the present invention, and Figure 1(B) is a side view thereof. The sealed chain 1 comprises a linear chain body 10 and an offset coupling link 2 connecting one end of the chain body 10 to the other end. The chain body 10 is an endless structure in which a plurality of inner links 11 and a plurality of outer links 12 are alternately connected. The inner links 11 include a pair of inner plates 13, a pair of bushings 14 and a pair of rollers 15. The outer links 12 include a pair of outer plates 16 and a pair of pins 17. In Figure 1 and some of the subsequent figures, the chain pitch direction TP, which is the extending direction of the sealed chain 1, the axial direction AX of the pins connecting the inner and outer links, and the chain width direction TW are indicated as directions.

[0024] The pair of inner plates 13 are both longitudinal plates in the chain pitch direction TP, and have an elliptical shape with a depression in the center of the longitudinal direction when viewed from the side. The pair of inner plates 13 are arranged parallel to each other. Bushing holes for bushings 14 are drilled at one end and the other end of the inner plates 13 in the longitudinal direction. The pair of inner plates 13 are connected by press-fitting both ends of the bushing 14 into the bushing holes. The bushing 14 has a through hole for inserting a pin 17. The roller 15 is rotatably fitted onto the bushing 14 between the pair of inner plates 13.

[0025] The pair of outer plates 16 are both longitudinal plates in the chain pitch direction TP, and have an elliptical shape with a depression in the center in the longitudinal direction when viewed from the side. The pair of outer plates 16 are arranged parallel to each other with the inner links 11 in between. Pin holes are drilled at one end and the other end in the longitudinal direction of each outer plate 16. The pair of outer plates 16 are connected by pressing both ends of a pair of pins 17 into the pin holes and then fixing them by crimping. The pins 17 are inserted through bushings 14, and both ends are fixed to the pin holes. The inner links 11 and outer links 12 are alternately connected by inserting the pins 17 into the bushings 14. As shown in Figure 1(B), the outer plates 16 are smaller in size than the inner plates 13. Specifically, in terms of the diameter of the arc portions at both ends in the longitudinal direction, the outer plates 16 have a smaller diameter than the inner plates 13, and the size of the central depression portion in the chain width direction TW is also smaller for the outer plates 16.

[0026] A lubricant, such as grease, is interposed between the pin 17 and the bushing 14, which are in a shaft-bearing relationship. The interposition of the lubricant reduces friction between the pin 17 and the bushing 14, making the bending motion of the seal chain 1 smoother, and also suppresses wear on the pin 17 and the bushing 14. To seal the lubricant between the pin 17 and the bushing 14, sealing materials (not shown) are placed at both ends of the bushing 14. The sealing materials are, for example, rubber ring seals, and are placed on the outer circumference of the bushing 14 between the inner plate 13 and the outer plate 16.

[0027] The offset coupling link 2 is a connecting member that connects one chain end E1 and the other chain end E2 of a linear chain body 10, forming an endless sealed chain 1. Both chain ends E1 and E2 have one end of a pair of outer plates 16 positioned at their respective end plates EP1 and EP2. The offset coupling link 2 connects these end plates EP1 and EP2.

[0028] [Overall structure of offset coupling link] Figure 2 is a partially broken front view of the offset joint link 2. The offset joint link 2 includes a pair of offset plates 3, a joint pin 41, a first bushing 42, a second bushing 43, a third bushing 44, a first roller 45, a second roller 46, a third roller 47, a sealing material 48, and an internal joint link 5.

[0029] The pair of offset plates 3 consists of a first offset plate 3A and a second offset plate 3B, which are arranged parallel to each other. The first offset plate 3A and the second offset plate 3B have the same shape. In the following description, unless there is a need to distinguish between the two plates 3A and 3B, they will simply be referred to as offset plate 3.

[0030] The offset plate 3 includes an outer plate portion 31, an inner plate portion 32, and an offset portion 33. The outer plate portion 31 has a pin hole 34 into which a coupling pin 41 is press-fitted. The inner plate portion 32 has a bushing hole 35 into which a first bushing 42 is press-fitted. The offset portion 33 connects the outer plate portion 31 and the inner plate portion 32, offset in the axial direction AX of the pin hole 34 and the bushing hole 35. The shape characteristics of the offset plate 3 will be described in detail below based on Figures 3 and 4.

[0031] The first offset plate 3A and the second offset plate 3B are positioned opposite each other with the offset directions of their outer plate portions 31 facing each other. In other words, the distance between the pair of outer plate portions 31 in the axial direction AX is longer than the distance between the pair of inner plate portions 32. One end of the joint inner link 5 is positioned between the pair of outer plate portions 31. That is, the outer plate portions 31 and the joint inner link 5 are connected in such a manner that one end of the joint inner link 5 is sandwiched between the pair of outer plate portions 31.

[0032] The internal link 5 of the joint is a link that connects one chain end E1 of the chain body 10 to the offset plate 3. The internal link 5 of the joint has the same configuration as the internal link 11 of the chain body 10 and includes a pair of parallel-arranged internal plates 51. The pair of internal plates 51 are connected by a second bushing 43 and a third bushing 44, which act as connecting members. One side of the pair of internal plates 51 in the chain pitch direction TP is connected by the second bushing 43, and the other side is connected by the third bushing 44. The pair of internal plates 51 have two bushing holes 52, into which the second bushing 43 and the third bushing 44 are pressed in, respectively.

[0033] The joint pin 41 connects the pair of outer plate portions 31 and also connects the offset plate 3 and the joint internal link 5. The joint pin 41 penetrates the pair of outer plate portions 31 and the joint internal link 5 in the axial direction AX. One end of the joint pin 41 in the axial direction AX is inserted into the pin hole 34 of the first offset plate 3A, and the other end is press-fitted into the pin hole 34 of the second offset plate 3B, and both are fixed by crimping.

[0034] The first bushing 42 connects a pair of inner plate portions 32. One end of the first bushing 42 in the axial direction AX is press-fitted into the bushing hole 35 of the first offset plate 3A, and the other end is press-fitted into the bushing hole 35 of the second offset plate 3B. The first bushing 42 has a first through hole 42H through which a pin 17 disposed at the other chain end E2 of the chain body 10 is inserted. The first roller 45 is rotatably fitted onto the first bushing 42 between the pair of inner plate portions 32.

[0035] The second bushing 43 has a second through-hole 43H through which the coupling pin 41 is inserted. One end and the other end of the second bushing 43 in the axial direction AX are press-fitted into the bushing holes 52 of a pair of inner plates 51 that constitute the coupling inner link 5. The second bushing 43 is fitted onto the coupling pin 41 and is rotatable around the coupling pin 41. A lubricant LU, such as grease, is interposed between the circumferential surface of the coupling pin 41 and the inner surface of the second through-hole 43H. The second roller 46 is fitted onto the second bushing 43 while positioned between the pair of inner plates 51.

[0036] The third bushing 44 has a third through-hole 44H through which a pin 17, which is disposed at one end E1 of the chain body 10, is inserted. One end and the other end of the third bushing 44 in the axial direction AX are press-fitted into the bushing holes 52 of the pair of inner plates 51, respectively. The third roller 47 is fitted onto the third bushing 44 while positioned between the pair of inner plates 51.

[0037] The sealing material 48 seals the lubricant LU interposed on the circumferential surface of the joint pin 41. The sealing material 48 is interposed between the outer plate portion 31 and the inner plate 51 of the joint inner link 5, around one side and the other side of the joint pin 41 in the axial direction AX. Note that the sealing material 48 is not shown in Figure 1(A). The sealing material 48 prevents the lubricant LU filled between the joint pin 41 and the second bushing 43 from leaking out. Note that although not shown in Figure 2, the sealing material 48 is also attached to the first bushing 42 and the third bushing 44.

[0038] [Detailed structure of the offset plate] Figures 3(A) and 3(B) are perspective views of the offset plate 3 from different perspective directions. Figure 4(A) is a side view of the offset plate 3, Figure 4(B) is a front view, and Figure 4(C) is a side view from the other side. The offset plate 3 includes an outer plate portion 31 and an inner plate portion 32 that are offset in the axial direction AX and aligned in the chain pitch direction TP, and an offset portion 33 that connects the outer plate portion 31 and the inner plate portion 32.

[0039] The inner plate portion 32 has a first surface P1 which is a plane facing the direction in which the outer plate portion 31 is offset, and a second surface P2 which is a plane facing the opposite direction to the first surface P1. The first surface P1 and the second surface P2 are parallel surfaces. Similarly, the outer plate portion 31 also has two surfaces that are parallel to each other. The bushing hole 35 is a hole that penetrates the inner plate portion 32 in the axial direction AX from the first surface P1 to the second surface P2. The pin hole 34 is a hole that penetrates the outer plate portion 31 in the axial direction AX. In the following description, the line connecting the center Oa of the pin hole 34 and the center Ob of the bushing hole 35 is called the pitch line PL. The direction of extension of the pitch line PL coincides with the chain pitch direction TP.

[0040] Figures 4(A) and 4(C) show the contour lines of the offset plate 3 in a side view, that is, the contour lines as seen from the axial direction AX. The offset plate 3 has a shape close to an ellipse, with the direction of extension of the pitch line PL as its longitudinal direction. The offset plate 3 comprises a pair of parallel line portions 301 that face each other in the axial direction AX, and a pair of arc portions 302 that face each other in the chain pitch direction TP.

[0041] The pair of parallel line sections 301 extend parallel to the pitch line PL, straddling the pitch line PL. The pair of arc sections 302 are located at both ends in the longitudinal direction of the offset plate 3 and have a semicircular outer shape. The pair of parallel line sections 301 extend along the entire length of the outer plate section 31, the offset section 33, and the inner plate section 32, excluding the pair of arc sections 302. Generally, the pair of parallel line sections 301 extend from the center Oa of the pin hole 34 to the center Ob of the bushing hole 35, with the portion outside the centers Oa and Ob being the arc section 302.

[0042] The pair of parallel line sections 301 do not necessarily have to extend over the entire length of the portion excluding the pair of arc sections 302, and may be arranged in a manner that spans a portion of the offset section 33. That is, the pair of parallel line sections 301 may extend through the offset section 33 to a portion that includes at least a part of the outer plate section 31 and the inner plate section 32. Furthermore, the pair of parallel line sections 301 do not have to be contour lines strictly parallel to the pitch line PL, and may be contour lines with a slight incline or contour lines with a slight convex or concave surface, as long as they can be treated as substantially parallel.

[0043] Referring to Figure 4(B), the offset amount of the outer plate portion 31 in the axial direction AX relative to the inner plate portion 32 is approximately equivalent to the thickness of the inner plate portion 32. The offset portion 33 is the part that fills the step difference between the outer plate portion 31 and the inner plate portion 32 based on the offset amount. As shown in Figure 4(A), on the first surface P1, the offset portion 33 is located on the side of the bushing hole 35 relative to the center line CL that divides the offset plate 3 in the longitudinal direction, and has a first curved surface R1 that is a gently convex curved surface toward the pin hole 34. On the other hand, as shown in Figure 4(C), on the second surface P2, the offset portion 33 is located on the side of the pin hole 34 relative to the center line CL, and has a second curved surface R2 that is a gently convex curved surface toward the bushing hole 35.

[0044] As shown in Figure 3(A), a seal seat 36 is recessed in the first surface P1 of the inner plate portion 32. The seal seat 36 is an annular recess concentric with the bushing hole 35. A seal material that seals lubricant between the first bushing 42 and the pin 17 inserted through the first bushing is seated in the seal seat 36. Note that Figure 2 shows a seal seat 36 provided on the inner plate 51 of the joint inner link 5, which performs a similar function to the inner plate portion 32. In other words, a seal material similar to the seal material 48 is fitted into the seal seat 36 in Figure 3(A).

[0045] As shown in Figure 3(B), an annular projection 37 is provided on the second surface P2 of the inner plate portion 32. The annular projection 37 is an example of a thickened portion that protrudes in the axial direction AX around the bushing hole 35. By providing the annular projection 37 as a thickened portion, the rigidity of the offset plate 3 can be increased. Since the annular projection 37 is an annular projection, even though its protruding length is small, it can increase the rigidity around the entire circumference of the bushing hole 35.

[0046] [Fracture resistance of offset plates] The offset plate 3 of this embodiment, having the above configuration, has excellent fracture resistance. This point will be explained with reference to Figure 5 and Figure 6, which shows a comparative example. Figure 5 is a diagram illustrating the warping forces F4 and F5 that occur in the offset plate 3 when a tensile force in the chain pitch direction TP is applied to the offset joint link 2.

[0047] The sealed chain 1 is stretched between the engine-side drive sprocket and the rear wheel-side driven sprocket of, for example, a motorcycle. When the sealed chain 1 is driven, tension is applied to the sealed chain 1 via the first roller 45 and the second roller 46. That is, as shown by the arrows in Figure 5, a tensile force F11 acts on the first roller 45 in one direction of the chain pitch direction TP, and a tensile force F12 acts on the second roller 46 in the opposite direction to the tensile force F11.

[0048] When a tensile force F11 is applied to the first roller 45, a tensile force F2 in the same direction as the tensile force F11 acts on each of the pair of inner plate portions 32. Also, when a tensile force F12 is applied to the second roller 46, a tensile force F3 in the same direction as the tensile force F12 acts on each of the pair of outer plate portions 31. As tensile forces F2 and F3 in opposite directions are applied to the outer plate portion 31 and the inner plate portion 32, stress concentrates in the offset portion 33, which is the part of the offset plate 3 where the shape changes in the axial direction AX.

[0049] Furthermore, when a tensile force F11 is applied to the first roller 45, the tensile force F11 also acts on the first bushing 42, which is fitted onto the first roller 45. As a result, the first bushing 42 bends slightly in an arc shape in the direction of the tensile force F11. This bending generates a warping force F4 that bends the inner plate portion 32 outward in the axial direction AX. In addition, as a reaction force to the warping force F4, a warping force F5 is generated that bends the outer plate portion 31 inward in the axial direction AX. Figure 5 illustrates the warping forces F4 and F5 applied to the first offset plate 3A, but similar warping forces are applied to the second offset plate 3B. These tensile forces F2 and F3 and warping forces F4 and F5 are forces that can cause the offset portion 33 or its vicinity to break.

[0050] Figure 6(A) is a side view of the offset plate 300 according to the comparative example, and Figure 6(B) is a front view showing the fracture state of a joint link using the offset plate 300 of the comparative example. The offset plate 300 includes an outer plate portion 310, an inner plate portion 320, and an offset portion 330. In the contour line viewed from the axial direction AX, the offset plate 300 has small arc portions 303 and large arc portions 304 located at both ends in the longitudinal direction, and a tapered portion 305 located between the small arc portion 303 and the large arc portion 304.

[0051] The small arc portion 303 is located near the end of the outer plate portion 310 and is an arc portion concentric with the pin hole 34. The large arc portion 304 is located near the end of the inner plate portion 320 and is an arc portion concentric with the bushing hole 35. The tapered portion 305 is a straight portion that fills the difference in diameter between the small arc portion 303 and the large arc portion 304. The contour line of the tapered portion 305 consists of a pair of inclined lines that are inclined with respect to the pitch line PL.

[0052] However, in a shape where there is a tapered section 305 from the inner plate section 320 to the outer plate section 310 in which the widthwise size decreases, and an offset section 330 is positioned in the middle of the tapered section 305, stress tends to concentrate in the offset section 330. In particular, stress concentration tends to occur on the outer plate section 310 side of the offset section 330 where the widthwise size is narrowed. For this reason, when tensile forces F2, F3 and warping forces F4, F5 as shown in Figure 5 are applied to the offset plate 300, a fracture section BR may occur relatively early near the offset section 330, as illustrated in Figure 6(B).

[0053] In contrast, the offset plate 3 of this embodiment has a shape in which a pair of parallel line portions 301 extending parallel to the pitch line PL extend from the inner plate portion 32 through the offset portion 33 to the outer plate portion 31. In other words, the offset plate 3 has a portion in which the outer plate portion 31 and the inner plate portion 32 have the same width in the chain width direction TW, with the offset portion 33 in between. As a result, the stress generated when the seal chain 1 is driven is distributed and reduced at the offset portion 33 and its vicinity, which is the connection point where the outer plate portion 31 and the inner plate portion 32 are connected. That is, stress concentration is less likely to occur at the offset portion 33, and fracture near the offset portion 33 can be suppressed. Therefore, premature fracture of the offset plate 3 can be suppressed.

[0054] In particular, the pair of parallel line portions 301 of the offset plate 3 extend along the entire length of the outer plate portion 31, the offset portion 33, and the inner plate portion 32, except for the arc portions 302 at both ends in the longitudinal direction of the offset plate 3. As a result, the outer plate portion 31, the offset portion 33, and the inner plate portion 32 have the same width along the entire length of the region of the offset plate excluding the arc portions 302. Consequently, stress distribution in the offset portion 33 is more easily achieved, and fracture of the offset plate 3 due to stress concentration can be further suppressed.

[0055] [Differentiation] Figure 7 is a perspective view showing the offset plate 3C according to the first modified example. The offset plate 3C has a different configuration from the seal seat 36 of the offset plate 3 illustrated in Figure 3(A) in the portion that accommodates the sealing material 48. The other components of the offset plate 3C are the same as those of the offset plate 3 described above, so their description is omitted.

[0056] The offset plate 3C has a circumferential wall 361, a wall portion 362, and a seal groove 363 on the first surface P1 of the inner plate portion 32. The circumferential wall 361 is a cylindrical wall for forming an annular recess around the bushing hole 35. The inner diameter of the circumferential wall 361 is set to be slightly larger than the outer diameter of the seal material 48. The wall portion 362 is a cylindrical wall that rises from the periphery of the bushing hole 35 in the axial direction AX within the recess formed by the circumferential wall 361. The end face of the wall portion 362 is at the same height as the first surface P1. The seal groove 363 is an annular groove formed between the circumferential wall 361 and the wall portion 362.

[0057] In the first modified offset plate 3C, a seal groove 363 is formed by a circumferential wall 361 that creates an annular recess around the bushing hole 35 and a wall portion 362 that protrudes from the periphery of the bushing hole 35. When the seal material 48 is placed in the seal groove 363, the outer circumference of the seal material 48 can be held by the circumferential wall 361 and the inner circumference by the wall portion 362. Therefore, the seal material 48 can be stably seated around the bushing hole 35. Furthermore, by forming the wall portion 362 on the periphery of the bushing hole 35, rigidity can be provided that contributes to suppressing warping of the inner plate portion 32. In addition, since the thickness in the axial direction of the peripheral portion of the bushing hole 35 is increased by the formation of the wall portion 362, the fitting width of the second bushing 43 can be made longer, which has the advantage of increasing the chain strength.

[0058] Figure 8 is a side view showing an offset plate 3D according to a second modified example. In the offset plate 3 described above, an annular projection 37 is exemplified as a thickened portion located on the second surface P2 of the inner plate portion 32. The offset plate 3D comprises a plurality of ribs as the thickened portion: a first rib 371, a second rib 372, a third rib 373, and a fourth rib 374. The configuration of the offset plate 3D other than the plurality of ribs is the same as that of the offset plate 3 described above.

[0059] The four ribs 371, 372, 373, and 374 are band-shaped projections that protrude axially AX from the bushing hole 35 and extend radially outward from the periphery of the bushing hole 35. The pair of ribs, the first rib 371 and the second rib 372, extend in opposite directions on the pitch line PL, flanking the bushing hole 35. The pair of ribs, the third rib 373 and the fourth rib 374, extend in opposite directions on the bushing hole 35, flanking the bushing hole 35, along a line perpendicular to the pitch line PL and passing through the bushing hole center Ob.

[0060] According to the second modified offset plate 3D, the rigidity near the bushing hole 35 can be increased by installing multiple ribs 371, 372, 373, and 374 on the second surface P2 of the inner plate portion 32. In particular, by arranging the first rib 371 and the second rib 372 on the pitch line PL, the offset plate 3D can effectively counteract the warping force caused by the tensile force when the seal chain 1 is driven. [Explanation of Symbols]

[0061] 1. Sealed chain (chain) 10. Chain body (linear chain) 2. Offset coupling links (coupling links) 3 Offset Plate 3A, 3B First offset plate, Second offset plate 301 Parallel line section 302 Arc section 31 Outer plate section 32 Inner plate section 33 Offset section 34 pin holes 35 bushing holes 36 Seal Seat 361 Peripheral wall 362 Wall 363 Seal groove (annular groove) 37 Annular projection (thickened portion) 371, 372, 373, 374: 1st rib, 2nd rib, 3rd rib, 4th rib 41. Connector pin (pin) 42 First Bush 43, 44 Second bushing, third bushing (connecting material) 45, 46, 47 First roller, second roller, third roller 48. Sealant 5. Internal link of joint (internal link) 51 Inner plate AX Axial direction TP chain pitch direction TW Chain width direction PL Pitch Line P1, P2 1st side, 2nd side Oa Pinhole center Ob Bush hole center

Claims

1. An offset plate used in a connecting link that connects both ends of a linear chain to form an endless chain, An outer plate portion having a pin hole into which a pin is press-fitted, An inner plate portion having a bushing hole into which a bushing is press-fitted, The outer plate portion and the inner plate portion are connected by an offset portion that is offset in the axial direction of the pin hole and the bushing hole, Viewed from the axial direction, the contour line of the offset plate has a pair of parallel line portions extending parallel to the pitch line connecting the center of the pin hole and the center of the bushing hole, An offset plate in which the pair of parallel line portions extend through the offset portion to a section including at least a portion of the outer plate portion and the inner plate portion.

2. In the offset plate according to claim 1, The offset plate has a shape in which the direction of extension of the pitch line is the longitudinal direction, and has arc portions at both ends in the longitudinal direction. An offset plate in which the pair of parallel line portions extend over the entire length of the outer plate portion, the offset portion, and the inner plate portion, excluding the arc portion.

3. In the offset plate according to claim 1, The inner plate portion has a first surface facing the direction in which the outer plate portion is offset, and a second surface opposite to the first surface. The bushing hole is a hole that penetrates from the first surface to the second surface, The inner plate portion is an offset plate having a thickened portion on the second surface that protrudes in the axial direction around the bushing hole.

4. In the offset plate according to claim 3, An offset plate in which the thickened portion is an annular projection that protrudes around the bushing hole.

5. In the offset plate according to claim 3, An offset plate in which the thickened portion is a plurality of ribs extending radially outward from the periphery of the bushing hole.

6. In the offset plate according to claim 5, An offset plate in which the plurality of ribs include a pair of ribs extending in opposite directions on the pitch line, flanking the bushing hole.

7. In the offset plate according to claim 1, The inner plate portion has a first surface facing the direction in which the outer plate portion is offset, and a second surface opposite to the first surface. The bushing hole is a hole that penetrates from the first surface to the second surface, The inner plate portion has the first surface, A peripheral wall that forms an annular recess around the bushing hole, Within the recess, a wall portion rises from the periphery of the bushing hole in the axial direction, An offset plate having an annular groove formed between the peripheral wall and the wall portion.

8. A first offset plate and a second offset plate comprising the offset plate described in any one of claims 1 to 7, A pin that is press-fitted into the aforementioned pin hole, A first bushing is press-fitted into the bushing hole, and a second bushing is fitted onto the pin. A first roller fitted onto the first bushing and a second roller fitted onto the second bushing, It comprises an inner link formed by connecting a pair of inner plates with a connecting member, The first offset plate and the second offset plate are arranged opposite each other with the offset directions of their respective outer plate portions reversed. One end of the inner link is positioned between the pair of outer plate portions. A coupling link wherein the pin penetrates a pair of outer plate portions and the inner link, the second bush is part of the connecting member of the inner link, and the second roller is positioned between the pair of inner plates.

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