Tensioner

Abstract

To provide a tensioner capable of generating stable damping force.SOLUTION: A tensioner includes a spiral spring for energizing a tensioning member. The spiral spring generates damping force by frictional force at sliding motion of a spirally wound leaf spring 21a. A sliding surface 21a1 of the leaf spring 21a includes a protrusion 31 having an end surface which serves as a sliding portion, and a recession 41 to which abrasion powder generated by sliding of the sliding portion is discharged.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a tensioner that adjusts the tension of an endless chain, belt, or the like. [Background technology]

[0002] Generally, a tensioner is used in a transmission device that uses a wrapped power transmission member such as a chain or belt to apply tension to the wrapped power transmission member on its slack side. Among such tensioners, a mechanical tensioner that uses a spiral spring is known (see Patent Document 1).

[0003] In a tensioner using this spiral spring, the spring's expanding force as it unwinds acts on the plunger, applying tension to the wound power transmission member via the tension arm. When the load from the tension arm becomes greater than the spring's expanding force, the spiral spring is wound up so that its diameter decreases. Furthermore, when the spiral spring is wound up or unwound, frictional force is generated between the leaf springs, generating a damping force that smoothly absorbs load fluctuations from the wound power transmission member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6600105 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the outer and inner circumferential surfaces of the leaf spring repeatedly slide back and forth due to the expansion and contraction of the spiral spring, the sliding parts wear and generate metal powder (hereinafter referred to as wear powder). If wear powder exists in the sliding parts, the frictional force generated between the leaf springs described above changes, and there is a risk that a stable damping force cannot be exerted.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a tensioner that is capable of generating a stable damping force. [Means for solving the problem]

[0007] One aspect of the present invention is a power transmission device comprising a tension member that receives a load from a wound power transmission body and a spiral spring that biases the tension member, wherein the spiral spring has spirally wound leaf springs. round trip The frictional force generated when sliding generates a damping force, and the sliding surface of the leaf spring has an end surface round trip a protrusion serving as a sliding portion; round trip The sliding part round trip A recess through which wear particles generated by sliding are discharged. The protrusions and recesses are formed on the outer peripheral surface of the spiral spring, and are not formed on the planar inner peripheral surface. The tensioner is characterized by: [Effects of the Invention]

[0008] To provide a tensioner capable of generating a stable damping force. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a front view showing a timing chain transmission device according to a first embodiment. [Figure 2] FIG. 1 is a front view showing a tensioner according to a first embodiment. [Figure 3] (a) Schematic diagram showing the plunger when it protrudes (when the mainspring is unwound), and (b) Schematic diagram showing the plunger when it is pushed in (when the mainspring is wound up). [Figure 4] 5A and 5B are schematic diagrams for explaining the process of generation of wear debris. [Figure 5] 1A is an enlarged view of the outer circumferential surface of the leaf spring having the surface texture according to the first embodiment, and FIG. 1B is a schematic view illustrating the movement of lubricating oil during sliding. [Figure 6] Schematic diagrams for explaining the mechanism of wear debris discharge, including (a) a diagram showing a state in which wear debris is present on the end face of a convex portion, and (b) a diagram showing a state in which wear debris has been discharged into a concave portion. [Figure 7]FIG. 10 is an enlarged view of the outer circumferential surface of a leaf spring to which a surface texture has been applied according to a second embodiment. [Figure 8] (a) An enlarged view of the outer peripheral surface of a leaf spring having a surface texture according to the third embodiment, (b) an enlarged view of the outer peripheral surface of a leaf spring having a surface texture with different convex shapes, (c) an enlarged view of the convex parts of FIG. 8(b), and (d) a diagram showing modified shapes of the convex parts. [Figure 9] FIG. 10 is a schematic diagram showing the surface texture of a leaf spring when the shape of the protrusions is elliptical. [Figure 10] FIG. 10 is an enlarged view of the outer peripheral surface of a leaf spring to which a surface texture has been applied according to a fourth embodiment. [Figure 11] A modified version of the leaf spring shown in Figure 10. [Figure 12] FIG. 4 is a schematic diagram showing grooves formed on the inner peripheral surface of the leaf spring. DETAILED DESCRIPTION OF THE INVENTION

[0010] First Embodiment An embodiment of the present invention will now be described with reference to the drawings. As shown in Fig. 1, a timing chain transmission device 10 disposed within an engine includes a sprocket 11a fixed to a crankshaft 11, sprockets 12a, 12a fixed to two camshafts 12, 12, and a timing chain 13 wound around the crank sprocket 11a and the cam sprockets 12a, 12a. Chain guides 14, 15 are in sliding contact with two locations on the tension side of the timing chain 13, which serves as a power transmission element, and a tensioner arm 16, which serves as a tensioning member, is in sliding contact with the slack side. The chain guides 14, 15 are fixed to the engine block, and one end of the tensioner arm 16 is pivotally supported by a support shaft 16b, with the other end abutting a plunger of a chain tensioner 17. The timing chain 13 can be any of a silent chain, roller chain, and bushing chain, and the support shaft 16b of the tensioner arm 16 may be located on either the upstream or downstream side in the running direction of the chain.

[0011] As shown in Figure 2, the chain tensioner (hereafter referred to as the tensioner) 17 has a body 19, which is fixed to a fixed member such as an engine block using mounting holes 19a, 19a and bolts. The body 19 has a through hole 19b on one side and a case portion 19c on the other side. A plunger 20 is slidably inserted into the through hole 19b, and a spiral spring 21 is housed in the case portion 19c. The spiral spring 21 is formed by spirally winding strip-shaped steel leaf springs 21a with rectangular cross sections so that the leaf springs are in contact with each other, with their outer ends fixed by outer end anchors 22 attached to the side surfaces 20b of the plunger 20 and their inner ends fixed to inner end anchors 23 fixed to the body 19.

[0012] A backup spring (member) 25 made of an arc-shaped leaf spring is disposed in the case portion 19c so as to support the inner peripheral surface of the spiral spring 21, and a guide piece 26 is fixedly provided so as to support the inner peripheral surface of one end (base end) of the backup spring 25. The inner end of the spiral spring 21 and the base end of the backup spring 25 are fastened together to the guide piece 26 fixed to the case portion 19c, and the inner peripheral surfaces of the spiral spring 21 and the backup spring 25 on the base end side are both supported by the guide piece 26. Therefore, the base end of the guide piece 26 serves as the inner end anchor 23. The spiral spring 21 is wound and fastened between the plunger 20 and the body 19 with a predetermined number of turns, and one end of the plunger 20 partially protrudes from the through hole 19b due to the biasing force of the spiral spring 21 to form a protruding portion (load receiving portion) 20a that abuts against the abutting portion 16a of the tensioner arm (tension member) 16.

[0013] Next, the operation of the tensioner 17 will be described. The inner end of the spiral spring 21 is fixed to the body 19 by the inner end anchor 23, and the biasing force acting to unwind and expand acts on the plunger 20, causing the tensioner 17 to apply a predetermined tension to the timing chain 13 via the tensioner arm 16. The tension of the timing chain 13 changes due to cam load fluctuations associated with engine rotation, and the load acting on the tensioner arm 16 also changes so as to constantly oscillate in accordance with the engine speed. When this load becomes smaller than the load (biasing force) based on the spiral spring 21, that is, when the force suppressing the diameter expansion of the spiral spring via the plunger becomes smaller, the plunger 20 protrudes (arrow a), as shown in FIG. 3(a), and therefore the outer end anchor 22 moves in the direction of arrow b, causing the spiral spring 21 to unwind so that its diameter expands as shown by arrow c. At this time, the spiral spring 21 expands in diameter, so that the frictional force between the spirally wound leaf springs is small, and the plunger 20 is protruded in a state where the resistance load is low.

[0014] When the load from the tensioner arm 16 becomes greater than the biasing force of the spiral spring 21, the plunger 20 is pushed in (arrow d) as shown in Figure 3(b), and therefore the outer end anchor 22 moves in the direction of arrow e, and the spiral spring 21 is wound up so that its diameter becomes smaller as shown by arrow f. At this time, because the spiral spring 21 contracts in diameter, the frictional force between the leaf springs becomes large, and a large resistance load due to this frictional force acts on the plunger 20.

[0015] The tensioner 17 has a hysteresis characteristic, with different loads when the plunger extends (arrow a) and when it retracts (arrow d). As a result, the load fluctuations on the tensioner arm 16 caused by the load vibration of the timing chain 13 due to engine rotation are buffered by the spiral spring of the tensioner 17, and are further damped and smoothly absorbed by the hysteresis characteristic caused by the difference in frictional force when the plunger extends and retracts.

[0016] When the difference in frictional force caused by the spiral spring 21 is insufficient to provide a sufficient damping effect, a backup spring (backup member) 25 is provided as in this embodiment. The backup spring 25 is supported at its base end by a guide piece 26 and is a leaf spring with one or more turns wound and a free end at its tip end. The backup spring 25 contacts the inner circumferential surface of the spiral spring 21 and supports the spiral spring 21 by exerting a biasing force in the radially outward direction as indicated by arrow g. As shown in FIG. 3(a), when the plunger 20 extends, the spiral spring 21 is supported by the backup spring 25 as indicated by arrow g and expands in the same direction as the arrow c, resulting in a small inter-plate frictional force. As shown in FIG. 3(b), when the plunger 20 is pressed in, the spiral spring 21 is sandwiched between the support force of the backup spring 25 in the direction of arrow g and the deformation force of the spiral spring 21 in the radially contracting direction f, resulting in a large inter-plate frictional force. This provides a large difference in inter-plate friction force between when the plate is pushed in and when the plate is pushed in, thereby providing the required damping effect.

[0017] <Surface texture of a spiral spring> Next, the surface texture of the spiral spring 21 will be described. Fig. 4 is a diagram for explaining the process of generation of wear powder, and is a schematic enlarged view showing the sliding state between outer peripheral surface 21a1' and inner peripheral surface 21a2' of a spiral spring according to a comparative example. As shown in Fig. 4, when the spiral spring is repeatedly unwound and wound in response to fluctuations in the load on the plunger, the spirally wound leaf spring 21a' undergoes reciprocating sliding between its outer peripheral surface 21a1' and inner peripheral surface 21a2' as indicated by the arrows in the figure.

[0018] Leaf spring 21a' is made of a highly elastic metal material, and when outer peripheral surface 21a1' and inner peripheral surface 21a2 slide against each other, the metal-to-metal contact causes wear, generating metal powder known as wear debris FD. As mentioned above, spiral spring tensioners generate damping force through friction between the leaf springs, so if such wear debris FD is present in the sliding portions of the leaf springs, the frictional force will change and the damping force may become unstable.

[0019] Furthermore, if sliding is repeated while wear debris FD is present in the sliding portion, the wear debris FD accelerates wear of the sliding portion, and the wear debris FD also grows in size. For this reason, it is desirable to expel the wear debris FD from the sliding portion as quickly as possible, but when outer peripheral surface 21a1' and inner peripheral surface 21a2', which are formed by flat surfaces, slide back and forth in close contact, the wear debris FD simply moves back and forth in the circumferential direction without moving significantly, and furthermore, it is difficult to supply lubricating oil between outer peripheral surface 21a1' and inner peripheral surface 21a2', which are in close contact with each other, so the wear debris FD is difficult to expel.

[0020] For this reason, in this embodiment, as shown in FIG. 5(a), an uneven surface texture is imparted to the outer peripheral surface 21a1 of the leaf spring 21a, which serves as a sliding surface. Specifically, in this embodiment, a plurality of convex portions 31 and concave portions 41 are provided in at least a portion of the outer peripheral surface 21a1 of the leaf spring 21a. In this embodiment, the inner peripheral surface 21a2 of the leaf spring 21a, which serves as the sliding surface opposite to the outer peripheral surface 21a1, is formed in a flat (plate) shape, and no uneven surface texture is imparted to the inner peripheral surface 21a2. However, the inner peripheral surface 21a2 may also be imparted with an uneven surface texture, similar to the outer peripheral surface 21a1. The uneven surface texture may be imparted by machining, such as etching, shot peening, laser processing, or tiling.

[0021] The plurality of protrusions 31 are each formed of a columnar protrusion (protrusion block), and are arranged in a plurality of protrusion rows (circumferential protrusion rows, vertical rows) in which the protrusions 31 are aligned in the circumferential direction C of the leaf spring 21a (longitudinal direction of the leaf spring 21a), and are aligned in the width direction D of the leaf spring 21a (short direction of the leaf spring 21a). More specifically, in this embodiment, the plurality of protrusion rows are arranged alternately in the width direction D, with first protrusion rows 311 in which the protrusions 31a are aligned in the circumferential direction C and second protrusion rows 312 in which the protrusions 31b are aligned such that their positions are shifted in the circumferential direction C from the first protrusion rows 311.

[0022] The first protrusion row 311 and the second protrusion row 312 are arranged at a predetermined interval in the width direction D so that the protrusions 31 a, 31 b do not overlap in the width direction D when viewed from the circumferential direction C. In addition, in the circumferential direction C, the protrusions 31 are positioned such that the protrusions of one protrusion row are positioned between the adjacent protrusions of the other protrusion row, and for example, the protrusion 31 a of the first protrusion row 311 is arranged so as to be positioned between the protrusions 31 b, 31 b of the adjacent second protrusion row 312 in the circumferential direction C, and the protrusion 31 b of the second protrusion row 312 is arranged so as to be positioned between the protrusions 31 a, 31 a of the adjacent first protrusion row 311 in the circumferential direction C.

[0023] Moreover, the recess 41 is configured by a plurality of grooves 41a, 41b formed between the plurality of protrusions 31. In this embodiment, the first protrusion row 311 and the second protrusion row 312 are arranged so that the protrusions 31a, 31b do not overlap in the width direction D, and therefore circumferential grooves 41a extending linearly in the circumferential direction C are formed between the first protrusion row 311 and the second protrusion row 312. Furthermore, widthwise grooves 41b extending in the width direction D are formed between the protrusions 31a, 31a of the first protrusion row 311 and between the protrusions 31b, 31b of the second protrusion row 312, and adjacent circumferential grooves 41a, 41a are connected to each other by the widthwise grooves 41b.

[0024] 5(b), in the present embodiment, on the outer peripheral surface 21a1, end faces (tip faces) 33 of the convex portions 31 serve as sliding portions that slide against the inner peripheral surface 21a2, and the load is supported by the end faces 33 of the plurality of convex portions 31. In addition, the circumferential grooves 41a and the widthwise grooves 41b (i.e., recesses 41) formed between the plurality of convex portions 31 serve as open spaces that communicate with the external space outside the inter-plate space between the outer peripheral surface 21a1 and the inner peripheral surface 21a2 of the leaf spring 21a, and serve as flow paths for the lubricating oil L of the spiral spring 21 (engine oil in this embodiment).

[0025] Therefore, when the outer peripheral surface 21a1 and inner peripheral surface 21a2 of the leaf spring 21a slide against each other, dynamic pressure is generated in the lubricating oil retained in the circumferential grooves 41a and widthwise grooves 41b, and the lubricating oil is supplied to the end faces 33 of the protrusions 31, which are the sliding contact points. In particular, because the circumferential grooves 41a and widthwise grooves 41b extend all the way to the center of the outer peripheral surface 21a1, lubricating oil L circulates from the external space into the inter-plate space. This ensures oil flow even to the end faces 33 of the protrusions 31 located in the center of the widthwise direction D of the outer peripheral surface 21a1, which is prone to boundary lubrication, preventing oil shortage. This reduces contact resistance between the outer peripheral surface 21a1 and inner peripheral surface 21a2 of the leaf spring 21a. Furthermore, the smooth flow of lubricating oil in the circumferential grooves 41a and widthwise grooves 41b improves cooling performance.

[0026] Furthermore, as shown in Fig. 6(a), even if wear debris FD occurs between the inner peripheral surface 21a2 of the leaf spring 21a and the end face 33 of the protrusion 31, the area of ​​the end face 33 of each protrusion 31 is small (the circumferential length L1 is short), and dynamic pressure is generated in the lubricating oil L as the protrusion 31 slides, ensuring oil flow at the end face 33. Therefore, the wear debris FD is swept away by the movement associated with the sliding and the lubricating oil L and discharged into the circumferential groove 41a or the widthwise groove 41b before it can grow large (see Fig. 6(b)). Note that the relationship between the circumferential length L1 of the end face 33 of the protrusion 31 and the reciprocating sliding distance L2 of the leaf spring 21a may be L1 ≥ L2, or L1 <L2でもよい。

[0027] In this way, in this embodiment, by imparting an uneven surface texture to the outer peripheral surface 21a1 of the leaf spring 21a, it is possible to prevent the outer peripheral surface 21a1 and the inner peripheral surface 21a2, which are the sliding surfaces, from coming into full contact with each other, and it is configured so that sufficient lubricating oil can be supplied to the end face 33 of the convex portion 31 that slides against the inner peripheral surface 21a2.

[0028] Furthermore, because oil flow to the end faces 33 of the protrusions 31 is ensured, wear debris FD generated on the end faces 33 of the protrusions 31 is discharged into the circumferential grooves 41a or widthwise grooves 41b, and is then discharged to the outside of the tensioner as the lubricating oil L circulates. These functions work together to reduce wear between the plates of the spiral spring 21, and also to ensure that a constant, stable damping force is exerted.

[0029] If no surface texture is applied, the wear debris FD may grow to several tens of μm in size, but in this embodiment, in order to discharge the wear debris FD before it grows, the height h (see FIG. 5) of the protrusions 31 is set to 0.5 μm or more, and in this embodiment, it is set to about 5 μm. Also, as shown in FIG. 5(b), the corners 35 formed by the end faces 33 and the peripheral surface 34 of the protrusions 31 are formed by rounded surfaces, which prevents edge chipping and stress concentration at the corners 35 and further reduces wear of the sliding portion 33 and the generation of wear debris FD.

[0030] In addition, because the degree of wear varies depending on the location of spiral spring 21, the arrangement or shape of convex portions 31 may be varied depending on the magnitude of the surface pressure or the ease of oil penetration. For example, when outer peripheral surface 21a1 of leaf spring 21a, which is the sliding surface, includes a first region and a second region that is different from the first region in circumferential direction C and has a lower surface pressure than the first region, convex portions 31 may be configured so that the sum of the areas of end faces 33 of convex portions 31 per unit area is larger in the first region than in the second region.

[0031] <Second embodiment> Next, a second embodiment will be described. The second embodiment differs from the first embodiment in that the surface texture of the spiral spring 21 is different. Therefore, in the following description, only the differences from the first embodiment will be described, and a description of the same configuration will be omitted.

[0032] In this embodiment, as shown in FIG. 7, the groove width of the circumferential groove is changed at the widthwise center and widthwise end portions of the leaf spring 21a, so that the flow speed of the lubricating oil L flowing through the circumferential groove is different at the widthwise center and widthwise end portions.

[0033] 7(a), at both widthwise ends of the leaf spring 21a, the first convex portion rows 311 and the second convex portion rows 312 are alternately arranged in the width direction D, as in the first embodiment. Meanwhile, at the widthwise center of the leaf spring 21a, convex portions 32b having circular end faces (tip faces) 33 with larger diameters than the convex portions 32a constituting the first convex portion row 311 and the second convex portion row 312 are aligned in the circumferential direction C to form a third convex portion row 313.

[0034] The distance between the first convex portion row 311 and the second convex portion row 312 is the same as in the first embodiment, and a first circumferential groove 41a1 is formed between the first convex portion row 311 and the second convex portion row 312. Meanwhile, a second circumferential groove 41a2 is formed between the convex portion row at the width direction end of the leaf spring 21a (the first convex portion row 311 in FIG. 7(a)) and the third convex portion row 313, which is the convex portion row at the width direction center.

[0035] The third convex portion row 313 and the first convex portion row 311 are arranged so that the distance in the width direction D between them is wider than the distance in the width direction between the first convex portion row 311 and the second convex portion row 312, and therefore the groove width of the second circumferential groove 41a2 is wider than the groove width of the first circumferential groove 41a1.

[0036] As a result, the flow rate of the lubricating oil L flowing through the second circumferential groove 41a2 becomes faster than the flow rate of the lubricating oil L flowing through the first circumferential groove 41a1, and the lubricating oil L is sucked from the outer sides in the width direction toward the second circumferential groove 41a2. In this way, by arranging the second circumferential groove 41a2, which has a faster flow rate, closer to the center in the width direction of the leaf spring 21a than the first circumferential groove 41a1, which has a slower flow rate, it is possible to efficiently draw a larger amount of lubricating oil between the leaves of the spiral spring 21.

[0037] Alternatively, as shown in FIG. 7(b), the third convex row 313 may be arranged at both widthwise ends of the leaf spring 21a, the first convex row 311 and the second convex row 312 may be arranged in the widthwise center portion, and the second circumferential groove 41a2, which has a faster flow rate, may be arranged further outward in the widthwise direction of the leaf spring 21a than the first circumferential groove 41a1, which has a slower flow rate. In other words, in the example shown in FIG. 7(b), the first circumferential groove 41a1 is a third circumferential groove extending in the circumferential direction C of the leaf spring 21a in the widthwise center portion of the leaf spring 21a, and the second circumferential groove 41a2 is a fourth circumferential groove extending in the circumferential direction further outward in the widthwise direction of the leaf spring 21a than the third circumferential groove. In this case, the lubricating oil L in the inter-plate space is more easily discharged outward from the inter-plate space, thereby efficiently discharging wear debris FD to the outside.

[0038] <Third embodiment> Next, a third embodiment will be described. The third embodiment differs from the first embodiment in that the surface texture of the spiral spring 21 is different. Therefore, in the following description, only the differences from the first embodiment will be described, and a description of the same configuration will be omitted.

[0039] 8(a), in this embodiment, the plurality of protrusions 31 are arranged in a manner that a plurality of protrusion rows (widthwise protrusion rows, horizontal rows) 314, 315 in which the protrusions 31 are aligned in the width direction D of the leaf spring 21a are lined up in the circumferential direction D of the leaf spring 21a. More specifically, in this embodiment, the plurality of protrusion rows are arranged alternately in the circumferential direction C, with a fourth protrusion row 314 in which the protrusions 31c are aligned in the width direction and a fifth protrusion row 315 in which the protrusions 31d are aligned such that their positions are shifted in the width direction from the fourth protrusion row 314.

[0040] The fourth convex portion row 314 and the fifth convex portion row 315 are arranged at a predetermined interval in the circumferential direction C so that the convex portions 31c, 31d do not overlap in the circumferential direction C when viewed from the width direction D. In addition, in the width direction D, the convex portions 31 are positioned such that the convex portions of one convex portion row are positioned between adjacent convex portions of the other convex portion row.

[0041] Moreover, the recess 41 is configured by a plurality of grooves 41a, 41b formed between the plurality of protrusions 31. In this embodiment, the fourth protrusion row 314 and the fifth protrusion row 315 are arranged so that the protrusions 31c, 31d do not overlap in the circumferential direction C, and therefore widthwise grooves 41b extending linearly in the width direction are formed between the fourth protrusion row 314 and the fifth protrusion row 315. Furthermore, circumferential grooves 41a extending in the circumferential direction are formed between the protrusions 31c, 31c of the fourth protrusion row 314 and between the protrusions 31d, 31d of the fifth protrusion row 315, and adjacent widthwise grooves 41b, 41b are connected to each other by the circumferential groove 41a.

[0042] In this way, in this embodiment, the widthwise groove 41b is formed in a linear manner and continuously to the widthwise end of the leaf spring 21a, thereby enabling the lubricating oil to circulate more effectively between the space between the plates and the outside.

[0043] In the above-described embodiment, the protrusions 31 are formed by columnar protrusions that are circular in plan view, but this is not limiting. For example, as shown in Figures 8(b) to 8(d), the protrusions 31 may be formed by protrusions that are polygonal in plan view. For example, as shown in Figures 8(b) and 8(c), the protrusions 31 may be triangular prism-shaped, or may be square prism-shaped with one side of the triangular prism bent inward. By doing so, anisotropy can be generated in the ease of flow of the lubricating oil L in the circumferential direction C.

[0044] Alternatively, as shown in FIGS. 9(a) to 9(f), the protrusions 31 may be configured to have an elliptical shape. For example, as shown in FIG. 9(a), forming the major axis of the ellipse parallel to the circumferential direction C of the leaf spring 21a can stabilize the flow of lubricating oil. As shown in FIG. 9(b), the protrusions 31 may be configured so that the major axis of the ellipse is parallel to the width direction D of the leaf spring 21a. In this case, the circumferential length of 33 is shortened, making it easier to discharge wear powder FD from the sliding portion. Furthermore, as shown in FIG. 9(c), the major axis of the ellipse may be configured to be inclined with respect to the circumferential direction C, and the arrangement may be staggered as shown in FIG. 9(d). Furthermore, the inclination direction of the major axis of the elliptical protrusions 31 may vary depending on the position. For example, the elliptical protrusions 31 may be arranged to form a V-shape as shown in FIGS. 9(e) and 9(f).

[0045] <Fourth embodiment> Next, a fourth embodiment will be described. The fourth embodiment differs from the first embodiment in that the surface texture of the spiral spring 21 is different. Therefore, in the following description, only the differences from the first embodiment will be described, and a description of the same configuration will be omitted.

[0046] In this embodiment, as shown in Fig. 10, the surface texture of the spiral spring 21 is formed by reversing the unevenness of the convex portions 31 and concave portions 41 in Fig. 1. That is, the portions that were convex portions in Fig. 5 are now multiple concave portions 410, and the portions that were concave portions 41 are now convex portions 310. Therefore, in this embodiment, each concave portion 410 becomes a closed space surrounded by the convex portions 310, and the lubricating oil L can be held in these multiple concave portions 410. In addition, the concave portions 410 function as foreign matter traps, and wear powder FD can be discharged into the concave portions 410.

[0047] In this embodiment, as shown in FIG. 12, it is preferable to provide a rail-shaped groove extending in the circumferential direction C, for example, on the inner surface 21a2 of the leaf spring 21a, which serves as the mating sliding surface, since this improves the circulation of the lubricating oil L between the recesses 410.

[0048] 11(a) to 11(d), the recesses 410 may be configured to communicate with the outside of the inter-plate space via grooves 411 to 414 and open to the outside. For example, as shown in FIG. 11(a), a groove 411 inclined relative to the circumferential direction may communicate between adjacent recesses 410 in a diagonal direction, and this groove 411 may extend to the end of the leaf spring 21a to communicate between the recesses 410 and the outside of the inter-plate space. Also, as shown in FIG. 11(b), grooves 412a and 412b with different inclination angles may communicate between adjacent recesses 410 in a diagonal direction and between the recesses 410 and the outside of the inter-plate space. Furthermore, as shown in FIG. 11(c), a groove 413 extending in the circumferential direction C may communicate between adjacent recesses 410 in a diagonal direction and between the recesses 410 and the outside of the inter-plate space. Furthermore, as shown in FIG. 11(d), grooves 414 extending in the width direction may be used to connect adjacent recesses 410 in the width direction with each other and to connect the recesses 410 with the outside of the inter-plate space.

[0049] In the above-described embodiment, the spiral spring 21 is configured such that the outer peripheral surface 21a1 and the inner peripheral surface 21a2 of the leaf spring 21a directly slide against each other, but for example, a friction material having a high friction coefficient (high μ material) may be interposed between the outer peripheral surface 21a1 and the inner peripheral surface 21a2 of the leaf spring in order to increase the frictional force when the leaf springs slide against each other. Furthermore, other functional materials (materials) that improve wear resistance or suppress heat generation may also be interposed.

[0050] For example, the outer peripheral surface of the backup spring 25 may also be provided with the above-described surface texture. Furthermore, while the present invention has been applied to a timing chain tensioner in the above-described embodiment, it is not limited to this application. It may also be applied to other engine-driven chains, such as balancers and hydraulic pumps, as well as belts for driving accessories. For belt tensioning, the present tensioner can be applied to tensioning pulleys, and can be used as a tensioner for adjusting the tension of any wrapped power transmission member. That is, in the above-described embodiment, the tensioner arm 16 is not limited to the arch-shaped one with a sliding surface for the chain 13 described above, but may be a tensioner arm with a tension pulley at its tip, or any tensioning member for tensioning a wrapped power transmission member. Furthermore, the inventions described in the above-described embodiment may be combined in any manner. [Explanation of symbols]

[0051] 13: Timing chain 16: Tensioner arm 21: Mainspring 31: Convex 41: Recess

Claims

1. a tension member that receives a load from the wrapped power transmission body; a spiral spring that biases the tension member, The spiral spring generates a damping force by frictional force generated when spirally wound leaf springs slide back and forth between each other, The sliding surface of the leaf spring is a protrusion having an end surface that serves as a reciprocating sliding portion; a recess into which wear powder generated by the reciprocating sliding portion is discharged, the protrusions and recesses are formed on the outer peripheral surface of the spiral spring, and are not formed on the planar inner peripheral surface; A tensioner characterized by:

2. the recessed portion includes a plurality of grooves formed between the plurality of protruding portions, The plurality of grooves serve as flow paths for lubricating oil for the spiral spring.

2. The tensioner of claim 1.

3. the plurality of protrusions are arranged in a manner that a plurality of protrusion rows are formed by aligning the protrusions in a circumferential direction of the leaf spring, and are aligned in a width direction of the leaf spring, The plurality of convex portion rows are arranged so as not to overlap with adjacent convex portion rows in the width direction when viewed from the circumferential direction of the leaf spring.

3. The tensioner of claim 2.

4. the plurality of protrusions are arranged in a circumferential direction of the leaf spring, such that a plurality of protrusion rows are formed by aligning the protrusions in a width direction of the leaf spring, The plurality of convex portion rows are arranged so as not to overlap with adjacent convex portion rows in the circumferential direction when viewed from the width direction of the leaf spring.

3. The tensioner of claim 2.

5. The plurality of grooves are a first circumferential groove extending in a circumferential direction of the leaf spring in a widthwise central portion of the leaf spring; a second circumferential groove extending in the circumferential direction on a width direction outer side of the leaf spring than the first circumferential groove, The first circumferential groove is formed to be wider than the second circumferential groove.

5. A tensioner according to any one of claims 2 to 4.

6. The plurality of grooves are a third circumferential groove extending in a circumferential direction of the leaf spring in a widthwise central portion of the leaf spring; a fourth circumferential groove extending in the circumferential direction on a width direction outer side of the leaf spring than the third circumferential groove, The fourth circumferential groove is formed to have a width wider than that of the third circumferential groove.

5. A tensioner according to any one of claims 2 to 4.

7. The convex portion has a circular, elliptical, or polygonal shape in plan view.

5. A tensioner according to any one of claims 1 to 4.

8. The protrusion has an elliptical shape in a plan view, and is formed so that the major axis of the elliptical shape is parallel to the circumferential direction of the leaf spring.

8. The tensioner of claim 7.

9. The convex portion has an elliptical shape in a plan view, and is formed so that the major axis of the elliptical shape is parallel to the width direction of the leaf spring.

8. The tensioner of claim 7.

10. The protrusion has an elliptical shape in a plan view, and is formed so that the major axis of the elliptical shape is inclined with respect to the circumferential direction of the leaf spring.

8. The tensioner of claim 7.

11. The convex portion has a corner formed by the end face and the side face, the corner having a rounded surface.

5. A tensioner according to any one of claims 1 to 4.

12. the sliding surface includes a first region and a second region that is different from the first region in the circumferential direction of the leaf spring and has a lower surface pressure than the first region, The convex portion is configured so that the sum of the areas of the end faces of the convex portion present per unit area is larger in the first region than in the second region.

5. A tensioner according to any one of claims 1 to 4.

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