JP4895185B2 - Chain noise prevention structure - Google Patents

Description

  The present invention relates to a noise prevention structure for a chain that is circulated between a driving sprocket and a driven sprocket. For example, in an internal combustion engine for an automobile, the torque of a crankshaft is transmitted to a camshaft of a valve mechanism. The present invention relates to a noise prevention structure for a chain used.

  Patent Document 1: Patent Literature 1: A chain drive device that includes a drive-side sprocket, a driven-side sprocket, and a chain that is looped between the sprockets and is used to transmit rotation of a crankshaft to a camshaft on a cylinder head in an internal combustion engine 1 is disclosed. In this apparatus, sliding portions between constituent members such as between adjacent plates constituting a chain are covered with a hard carbon thin film having a low hydrogen content such as diamond-like carbon (DLC). As a result, the frictional resistance and the amount of wear between the above-mentioned members are reduced under the lubricating oil, and the noise and friction loss during operation are reduced.

JP 2005-61441 A

  By the way, the path of the chain driven to circulate between the driving side sprocket and the driven side sprocket is generally on one plane. However, when used for a long time, due to aging, the chain will run out in the width direction, that is, in the direction away from this plane. This causes noise from the chain.

  However, in the chain drive device described in Patent Document 1, in order to reduce the frictional resistance and the amount of wear of the sliding portions between the constituent members, such a portion is merely covered with a hard carbon film. The runout that occurs in the chain cannot be suppressed. Therefore, the device cannot prevent noise generation.

  Therefore, an object of the present invention is to provide a noise prevention structure for a chain that prevents the occurrence of noise due to such chain runout.

  In order to achieve the above object, a noise prevention structure for a chain according to the present invention is a chain constructed by circulatingly driving between a drive side sprocket and a driven side sprocket and alternately connecting an inner link and an outer link. The inner link plate and the outer link are at least one of an outer surface of the inner link plate of the inner link and an inner surface of the outer link plate of the outer link facing the outer surface. A gap reducing member for reducing the gap with the plate is provided. According to this configuration, the gap between the inner link plate and the outer link plate is reduced in at least one of the outer surface of the inner link plate of the inner link and the inner surface of the outer link plate of the outer link facing the outer surface. Therefore, the inner link plate and the outer link plate are prevented from being relatively inclined. Therefore, the occurrence of vibration in the chain width direction in the chain is suppressed, and noise can be prevented from being generated.

  In order to achieve the above object, another chain noise prevention structure according to the present invention is a chain noise prevention structure that is driven to circulate between a drive side sprocket and a driven side sprocket. A first guide member that guides the chain portion from the outside of the circulation path by contacting a chain portion located downstream of the sprocket and upstream of the driven sprocket, and the chain portion between the first guide member and the first guide member And a second guide member abutting on the chain portion from the inside of the circulation path so as to sandwich the chain. According to this configuration, the first guide member that guides the chain part by contacting the chain part located on the downstream side of the drive side sprocket and the upstream side of the driven side sprocket from the outside of the circulation path, and the first guide member Since the second guide member that abuts the chain portion from the inside of the circulation path so as to sandwich the chain portion therebetween, tension is exerted on the chain portion in substantially different directions by the first guide member and the second guide member. At the same time, the chain portion is sandwiched between the first guide member and the second guide member. Therefore, the runout of the chain can be appropriately suppressed, and noise can be prevented from being generated.

  In particular, the second guide member has a chain contact start point in the second guide member located downstream of the chain disengagement point in the drive side sprocket and upstream of the chain contact start point of the first guide member. It is good to be arranged. As a result, the chain part detached from the drive side sprocket is first contacted from the inside of the circulation path by the second guide member, and then contacted from the outside by the first guide member.

  The second guide member is arranged such that a chain portion between the chain disengagement point in the driving side sprocket and the chain contact end point in the first guide member is curved in an S shape. preferable. By doing this, the chain portion from which the drive side sprocket is detached is first given tension as it curves toward the outside of the circulation path, and tension is given as it curves toward the inside of the circulation path. Become.

  The chain noise prevention structure of the present invention will be described below based on the embodiments. The following description will be made by applying the present invention to a chain drive device that transmits power from a crankshaft of an in-vehicle engine to intake and exhaust camshafts of a valve operating mechanism.

  First, it demonstrates based on 1st Embodiment. The front structure of the chain drive device 10 is shown in FIG. The endless chain 12 is wound around two cam sprockets 14 and 16 respectively connected to the intake side and exhaust side cam shafts of the in-vehicle engine and a crank sprocket 18 of the in-vehicle engine. In this chain drive device 10, the chain 12 travels from the crank sprocket 18 through the cam sprocket 14 and the cam sprocket 16 in this order, as shown by the arrow in FIG. It has become. The chain 12 is driven to circulate between them in order to transmit the crankshaft rotational force or power from the crank sprocket 18 to the cam sprockets 14, 16 and further to the intake and exhaust camshafts. The crank sprocket 18 is a drive side sprocket, and the cam sprockets 14 and 16 are driven side sprockets.

  Between the cam sprockets 14 and 16 and the crank sprocket 18, chain guides 20 and 22 for restricting the displacement in the width direction of the chain 12 spanned between them are respectively arranged. The chain guides 20 and 22 guide arbitrary portions of the chain 12 so as to direct them in a predetermined direction. The chain guide 20 disposed between the crank sprocket 18 and the cam sprocket 14 is urged by the tensioner 24 toward the side pressing the chain 12, that is, from the outside to the inside of the circulation path P of the chain 12. ing. And the tension | tensile_strength (tension) is provided to the chain 12 by the urging | biasing.

  In this chain drive device 10, the chain winding position of the two cam sprockets 14 and 16 and the chain winding position of the crank sprocket 18 are positioned on the same plane. That is, in the chain drive device 10, the sprockets 14, 16, 18 are arranged so that the teeth of the cam sprockets 14, 16 and the teeth of the crank sprocket 18 are located on the same plane. Therefore, the circulation path P of the chain 12, that is, the traveling track of the chain 12, is located on one plane. Conceptually in FIG. 1, the chain 12 has its circulation path P on the page.

  Further, in this chain drive device 10, lubricating oil is supplied to the chain 12. In the first embodiment, the lubricating oil injected and supplied at the portion where the chain 12 is wound around the crank sprocket 18 is near the inlet portion of the chain guide 22, that is, near the upper end portion of the chain guide 22 in FIG. The chain 12 is supplied by being wound around.

  FIG. 2 shows a perspective view of a part of the chain 12. FIG. 3 shows an exploded perspective view of a part of the chain 12 of FIG. As is apparent from the drawing, in this chain drive device 10, a roller type chain is employed as the chain 12. The chain 12 is formed by alternately connecting inner links 26 and outer links 28. That is, the chain 12 is formed by connecting adjacent inner links 26 with an outer link 28.

  Each inner link 26 includes two bushes 30, two rollers 32, and two inner link plates 34 on the left and right. Each inner link 26 is formed by rotatably disposing a roller 32 on the outer periphery of the bush 30 and then press-fitting both ends thereof to the inner link plate 34.

  On the other hand, each outer link 28 includes two pins 36 and two right and left outer link plates 38. Both ends of the pin 36 of the outer link 28 are press-fitted and fixed to the outer link plate 38 in a state of being inserted into the bush 30 of the inner link 26 connected to the front and rear of the pin 36, respectively.

  As shown in FIG. 3, a clearance reduction member S is attached to the outer surface 40 of the inner link plate 34. The clearance reduction member S is a member that prevents the inner link plate 34 and the outer link plate 38 from being relatively inclined, and will be described in detail later. The outer surface 40 of the inner link plate 34 is a surface in which the inner link 26 and the outer link 28 are alternately connected, and the outer link plate 38 overlaps thereon. When assembled, the inner link plate 34 and the outer link plate 38 are attached so that the outer surface 40 of the inner link plate 34 and the inner surface 42 of the outer link plate 38 are shifted by a predetermined amount and overlap each other. A gap reducing member S is attached to the opposing outer surface 40.

  The clearance reducing member S reduces a clearance (clearance) C between the inner link plate 34 and the outer link plate 38. In the connected state, the outer surface 40 of the inner link plate 34 and the inner surface 42 of the outer link plate 38 are placed at a slight distance, and therefore a gap C is formed. In order to reduce the gap C, the gap is reduced. The member S is provided so as to protrude from the outer surface 30 of the inner link plate 34 in the width direction of the chain 12. The gap reducing member S has a predetermined thickness.

  In particular, in the first embodiment, the gap reducing member S is provided so as to fill the gap C between the inner link plate 34 and the outer link plate 38, so that the gap reducing member S is not only in contact with the inner link plate 34. The outer link plate 38 is also in contact. However, the thickness of the gap reducing member S is designed so that the smooth movement of the inner link 26 and the outer link 38, that is, the smooth rotation of the chain 12 is not hindered.

  In the first embodiment, Teflon (registered trademark), which is a low friction material, is used as the gap reducing member S. More specifically, a Teflon sheet having a predetermined thickness and cut into a predetermined size and shape is attached to the outer surface 40 of the inner link plate 34. The Teflon sheet is attached by pasting using an adhesive, and the gap reducing member S is fixed. When the outer link plate 38 is connected so as to overlap the outer surface 40 of the inner link plate 34 to which the gap reducing member S made of a Teflon sheet is attached, the gap reducing member S includes the inner link plate 34, the outer link plate 38, and the like. And is in contact with these. The clearance reducing member S receives a compressive force from the inner link plate 34 and the outer link plate 38 that are very small. In the case of the first embodiment, the clearance reducing member S provided on the inner link plate 34 contacts the outer link plate 38 but is not fixed thereto, so that the clearance reducing member S and the outer link are rotated by the rotation of the chain 12. An oil film is formed between the plate 38 and the plate 38. Thereby, the movement of the chain 12 is appropriately maintained smoothly.

  Next, the function and effect of the first embodiment will be described. FIG. 4 is a conceptual diagram of the chain 12 for explaining the function and effect, and shows the relative inclination between the inner link plate 34 and the outer link plate 38 which are constituent members thereof. In FIG. 4, only the inner link plate 34, the pin 36, and the outer link plate 38 are extracted and shown. The inner link plate 34 and the outer link plate 38 are represented by solid lines, the pins 36 are represented by dotted lines, The element is omitted. Further, the traveling direction of the chain 12 is indicated by a white arrow. As shown in FIG. 4A, at the beginning of use, the inner link plate 34 and the outer link plate 38 are arranged substantially in parallel, and the chain 12 is straight without being swung in the width direction in a predetermined traveling direction. Move. When the clearance reducing member S is not provided between the inner link plate 34 and the outer link plate 38, the clearance C remains as it is (see FIG. 4A). When used for a long time in this state, for example, periodic tension strength due to opening and closing of the intake and exhaust valves is transmitted from the cam sprockets 14 and 16 to the chain 12, and the inner link plate 34 and the outer link plate 38 are inclined to each other. It comes to occur. Specifically, the inner link plate 34 and the outer link plate 38 are not parallel to each other, and a tendency to tilt in a direction different from the traveling direction is recognized (see FIG. 4B). When the chain 12 is rotated in such a state, the components of the chain 12 are shaken, as if the chain 12 meanders in the width direction. Then, the inner link plate 34 and the outer link plate 38 are partially rubbed or collided during traveling, or noise is generated by colliding with other members.

  Therefore, as described above, the gap reducing member S is provided so as to reduce the gap C, and the inner link plate 34 and the outer link plate 38 are prevented from being relatively inclined as shown in FIG. 4 (c)). By doing so, the inner link plate 34 and the outer link plate 38 are restrained in the chain width direction, that is, the direction orthogonal to the traveling direction. As a result, the inner link plate 34 and the outer link plate 38 are restrained from swinging in the chain width direction. Further, since the gap reducing member S made of a Teflon sheet has elasticity, even if a force in the chain width direction acts on the inner link plate 34 or the outer link plate 38 by this elastic force, the force can be absorbed and reduced. It becomes possible. Therefore, the tendency that the chain 12 meanders in the width direction of the inner link plate 34 and the outer link plate 38 is suppressed, and the generation of noise is appropriately prevented.

  As described above, in the first embodiment, the clearance reducing member S is provided on the substantially arc-shaped portion of the outer surface 40 of the inner link plate 34 on both end sides before and after the traveling direction (see FIG. 3). However, the location where the clearance reducing member S is provided and the shape thereof may be other than this. FIG. 5 schematically shows the position where the gap reducing member S is arranged and the shape of the gap reducing member S. FIG. 5A shows the above embodiment. In the modification of FIG. 5B, the gap reducing member S1 is provided in a ring-shaped portion around the hole 34a into which the bush 30 is inserted, in the outer surface 40. Further, as shown in FIG. 5C, a plurality of gap reducing members S2 may be arranged around the hole 34a, and are attached separately in the front and rear directions in this case. Needless to say, the gap reducing member S3 may be provided so that the entire outer surface 40 of the inner link plate 34 is covered with the gap reducing member S3 as shown in FIG. 5D. The gap reducing member S (including S1, S2, and S3) is preferably made of Teflon (registered trademark) as described above, but the gap reducing member S may be made of other materials. . For example, it can be produced from other materials that absorb impact, elastic materials, low friction materials having a friction coefficient of 0.1 or less, and the like.

  If the clearance reducing member S is provided so as to reduce the clearance C between the inner link plate 34 and the outer link plate 38, the clearance reducing member S is not limited to being provided on the inner link plate 34 as described above. It may be provided on the inner surface 42. In addition, although the pattern as shown in FIG. 5 is possible for the attachment location and the shape of the clearance reduction member S, other than that may be sufficient. Further, the clearance reducing member S may be provided on both the inner link plate 34 and the outer link plate 38.

  Next, a second embodiment will be described. In the second embodiment, in addition to the first embodiment, a chain guide that contacts the chain from the inner side to the outer side of the circulation path P is further provided. Since the second embodiment includes the same components as the components of the first embodiment, in the following description, the same components as those described above are denoted by the same reference numerals and description thereof is omitted.

  The chain drive device 110 according to the second embodiment is spanned between the cam sprockets 14 and 16 and the crank sprocket 18 and regulates the chain 12 having the clearance reducing member S and the displacement of the chain 12 in the width direction. The chain guides 20 and 22 for guiding the chain guide 20 and the tensioner 24 for urging the chain guide 20 from the outside to the inside of the circulation path P of the chain 12 and the chain 12 to the outside from the inside of the circulation path P The chain guide 50 is urged toward the end.

  First, the chain guide 50 will be schematically described with reference to FIG. FIG. 6 is a conceptual diagram partially showing the periphery of the place where the chain guide 50 is provided. FIG. 6A shows a state before the chain guide 50 is provided, and FIG. 6B shows the chain guide. The state where 50 is provided is shown. The chain guide 50 is provided to cooperate with the chain guide 20. The chain guide 50 is a chain as a first guide member that contacts the chain portion 12a of the chain 12 located downstream of the crank sprocket 18 and upstream of the cam sprocket 14 from the outside of the circulation path P to guide the chain portion 12a. The second guide member is in contact with the chain portion 12a from the inside of the circulation path P so as to sandwich the chain portion 12a with the guide 20.

  In particular, the chain guide 50 in contact with the chain portion 12a is disposed upstream of the chain guide 20 in the chain traveling direction. Here, the fact that the chain guide 50 is arranged upstream of the chain guide 20 means that the chain portion 12a that has been released from the meshed state with the crank sprocket 18 first comes into contact with the chain guide 50 and then contacts the chain guide 20. This means that the chain guides 20 and 50 are positioned to contact each other. That is, the chain 12 contact start point (chain contact start point) T1 in the chain guide 50 is downstream of the chain 12 release point (chain release point) G1 in the crank sprocket 18 and the chain contact start point in the chain guide 20. The chain guide 50 is disposed so as to be positioned on the upstream side of T2. The “chain contact start point” refers to a position where an arbitrary part of the rotating chain 12 starts to contact. Further, the “chain detachment point” refers to a position where an arbitrary part of the rotating chain 12 is separated from a contact state such as a meshing state.

  In the second embodiment, the chain guide 20 exerts tension on the chain 12 so that the chain 12 is curved inward of the circulation path P, and the chain guide 50 causes the chain 12 to move outside the circulation path P. The chain 12 is tensioned so as to be bent. Therefore, as shown in FIG. 6B, the chain portion between the chain disengagement point G1 in the crank sprocket 18 and the contact end point (chain contact end point) G2 of the chain 12 in the chain guide 20 is substantially S-shaped. To be curved. In FIG. 6B, the chain portion 12a is curved opposite to the S-shape, but is curved in an S-shape when viewed from the opposite side. By doing so, the chain portion 12a from which the crank sprocket 18 is detached is first tensioned toward the outside of the circulation path P and then tensioned toward the inside of the circulation path P. Is reliably prevented from being loosened, and the chain 12 is prevented from being shaken. The “chain contact end point” refers to a position where an arbitrary part of the rotating chain 12 ends contact.

  A perspective view of the chain guide 50 in the middle of being attached to the chain guide 20 is shown in FIG. In addition, the white arrow in FIG. 7 represents the chain traveling direction. Further, FIG. 8 conceptually shows a state in which the chain portion 12 a is sandwiched between the chain guide 20 and the chain guide 50. Moreover, although the sectional view on the AA line of FIG. 8 is shown in FIG. 9, the chain 12 is abbreviate | omitted in FIG. The chain guide 20 and the chain guide 50 are configured separately and assembled and integrated. The chain guide 50 includes a first connecting member 52, a second connecting member 54, and a rotating member 56 that is sandwiched and attached therebetween (see FIG. 9). Although the second connecting member 54 is shown in FIG. 9, it is omitted in FIGS. 7 and 8 for easy understanding.

  The first and second connecting members 52 and 54 are configured so that a part of the circulation path P of the chain 12, that is, the travel path R of the chain 12 is formed between the chain guide 20 and the rotating member 56. It is attached to the chain guide 20 with 20 therebetween. Here, the attachment is performed using a screw member, that is, the bolts 58 and 60 shown in the drawing. In addition, the space | interval between the 1st connection member 52 and the 2nd connection member 54 in the assembled state is slightly larger than the space | interval between the two outer link plates 38 in one outer link 28 of the chain 12. . The first connecting member 52 is provided with a column 62. The column portion 62 has a predetermined length so that the protruding tip portion 64 contacts the second connecting member 54 in the assembled state. In addition, the support | pillar part 62 is not restrict | limited to being provided in the 1st connection member 52, For example, you may provide in the 2nd connection member 54. FIG.

  The rotating member 56 is attached between the first connecting member 52 and the second connecting member 54 with a play, that is, with a predetermined minute interval C1. Further, the rotating member 56 has a through hole 66. A fastening bolt 67 inserted from the fastening hole 68 of the second connecting member 54 is inserted into the through hole 66, and the tip end portion of the fastening bolt 67 protrudes from the fastening hole 70 of the first connecting member 52 and is a nut. 72 and screwed together. Thus, the rotating member 56 has play in the thickness direction thereof, that is, in the direction in which the first connecting member 52 and the second connecting member 54 face each other, and between the first and second connecting members 52, 54. Attached to. Therefore, the rotation member 56 can rotate around the axis L of the fastening bolt 67. As shown in FIGS. 7 and 9, a rubber bush that fills a gap between the fastening bolt 67 and the through-hole 66 on the outer periphery of the fastening bolt 67 so as not to hinder the movement of the rotating member 56. 74 is disposed. Therefore, the rotation member 56 is allowed to move depending on the elasticity of the rubber bush 74.

  The rotation member 56 further includes a contact portion 76 that contacts the chain 12 and an extending portion 78 that extends from one end side of the contact portion 76. The extending portion 78 extends around the cylindrical portion 80 that defines the through hole 66, and includes a rotating support portion 82. The pivot post 82 is provided in parallel with the post 62, and the projecting tip 84 is close to the second connecting member 54 in an assembled state. The total thickness of the rotating column part 82 and the extending part 78 is equal to the thickness of the contact part 76.

  And the rotation member 56 is provided with the spring member 86 (refer FIG. 8) in order to press the contact part 76 of the rotation member 56 against the chain 12. FIG. In FIG. 9, the spring member 86 is omitted. In the second embodiment, the spring member 86 is a leaf spring. One end of the spring member 86 is fixed to the column portion 62, and the other end is fixed to the rotating column portion 82 via the cylindrical portion 80. In such a state, the spring member 86 is configured to store a stretching force. Therefore, as conceptually shown in FIG. 10, the rotary support 82 is urged from the spring member 86 toward the chain guide 20. Will be. By urging the rotating support column 82 toward the chain guide 20, the rotating member 56 rotates approximately within a predetermined angle about the axis L of the fastening bolt 67. However, since the length from the cylindrical part 80 to the end part 76a of the contact part 76 is longer than the length from the cylindrical part 80 to the support | pillar part 62, even if it is the state where the chain 12 was removed, it is a rotation member. 56 is rotated only until its end portion 76 a comes into contact with the support 62. In the second embodiment, the other end of the rotating member 56 is in contact with the chain guide 20 while one end of the rotating member 56 is in contact with the support 62.

  Each component is positioned as described above, and the rotating member 56 is biased by the spring member 86, so that the contact portion of the chain guide 50 is in a state where the chain 12 is rotated as shown in FIG. A line B1 having an inclination angle of 76 and a line B2 having an inclination angle of the chain guide 20 have a predetermined angle α. Therefore, the chain portion 12 always comes into contact with the chain guide 50 and then comes into contact with the chain guide 20. The predetermined angle α varies within a minute range due to vibrations from the chain 12 and the like.

  Next, the function and effect of the second embodiment will be described. When the chain 12 travels on the travel path R between the chain guide 20 and the rotation member 56, the chain portion 12a that has been disengaged from the meshed state with the crank sprocket 18 as shown in FIG. Particularly, in contact with the rotating member 56, the chain 12 is pressed from the inside to the outside of the circulation path P to apply an outward tension (a white arrow M1 in FIG. 8). Then, on the downstream side, the chain portion 12a comes into contact with the chain guide 20 and is pressed from the outside to the inside of the circulation path P of the chain 12 to apply inward tension (FIG. 8). Inside white arrow M2). Accordingly, the chain 12 is subjected to a predetermined tension inward and outward of the circulation path P by the rotating member 56 and the chain guide 20 of the chain guide 50, and the chain 12 is connected to the rotating member 56 and the chain guide 20. Therefore, even if the chain 12, particularly the chain portion 12 a sways due to meshing with the crank sprocket 18, the sway is reduced and suppressed. Note that this is effective in reducing a noticeable shake when the interlink plate 34 and the outer link plate 38 tend to be inclined with respect to each other as shown in FIG. 4B.

  Further, the distance between the first connecting member 52 and the second connecting member 54 in the state of being attached to the chain guide 20 is larger than the distance between the two outer link plates 38 in one outer link 28 of the chain 12. Is slightly larger, it is possible to further reduce and suppress the swing of the chain 12. In particular, this reduces the mutually inclining forces acting on the interlink plate 34 and the outer link plate 38 (see FIG. 4B), or suppresses the movement of the chain 12 due to such forces. It becomes possible.

  Therefore, by providing the chain guides 20 and 50 so as to cooperate with each other, it is possible to reduce the force that causes the chain 12 to sway and the sway thereof. When the chain 12 having the inner link plate 34 and the outer link plate 38 having a tendency to be inclined as shown in FIG. 4B is used, the vibration caused by the meshing with the crank sprocket 18 is appropriately prevented. Since it can reduce, it becomes possible to prevent that tendency becoming remarkable. As a result, noise due to the chain 12 can be reduced.

  Further, as described above, the rubber bushing 74 that fills the gap between the fastening bolt 67 and the through hole 66 is disposed on the outer periphery of the fastening bolt 67. Movements that depend on the elastic range are allowed. Accordingly, the vibration of the chain 12 is further reduced and absorbed by the rubber bush 74, and the vibration of the chain can be more appropriately reduced.

  As described above, in the second embodiment, the chain portion 12a detached from the crank sprocket 18 is first given the outward tension of the circulation path P by the chain guide 50 and then the inward of the circulation path P by the chain guide 20. By applying tension and continuously passing the chain portion 12a between them, in other words, by applying such tension to the chain 12a and sandwiching it between the chain guide 50 and the chain guide 20, It was decided to reduce the runout of the chain portion 12a. However, the chain portion 12a may not be directly sandwiched between the chain guide 50 and the chain guide 20, and may be delivered.

  The chain guide 20 and the chain guide 50 may not be integrated. The chain guide 20 and the chain guide 50 are positioned so that the tension is applied to the chain 12 as described above by the chain guide 20 and the chain guide 50, and the chain guide 20 and the chain guide 50 are controlled so as to suppress the vibration generated in the chain 12 as described above. May be provided independently. Further, the spring member 86 is not limited to a leaf spring, and may be composed of various spring materials. Furthermore, in the case of the second embodiment, one of the first connecting member and the second connecting member 54 may be omitted.

  Further, in the second embodiment, the gap reducing member S is provided. However, the gap reducing member S may not be provided. In other words, the swing of the chain 12 may be suppressed by using only the first guide member and the second guide member without using the gap reducing member S.

  In the above embodiment, the present invention has been described with a certain degree of concreteness, but various modifications and changes can be made to the present invention without departing from the spirit and scope of the invention described in the claims. It must be understood that. That is, the present invention includes modifications and changes that fall within the scope and spirit of the appended claims and their equivalents.

It is the schematic which shows the front structure of the chain drive device with which 1st Embodiment was applied. It is a perspective view of a part of chain in a 1st embodiment. FIG. 3 is an exploded perspective view of a part of the chain of FIG. 2. It is a conceptual diagram for demonstrating the effect of 1st Embodiment. (A) is a figure which shows the attachment position of the clearance reduction member of 1st Embodiment, (b)-(d) is the figure which showed the other example. It is a conceptual diagram for demonstrating 2nd Embodiment, (a) represents the state before providing the 2nd guide member, (b) represents the state which provided it. It is a conceptual perspective view in the middle of assembling the 2nd guide member of 2nd Embodiment. It is a figure showing notionally the state where the chain part contacted the 2nd guide member. It is the sectional view on the AA line of FIG. It is the figure which showed conceptually the provision of the force by a spring member.

Explanation of symbols

10, 110 Chain drive device 12 Chain 12a Chain portion 14, 16 Cam sprocket 18, Crank sprocket 20, 22, 50 Chain guide 26 Inner link 28 Outer link 30 Bush 32 Roller 34 Inner link plate 36 Pin 38 Outer link plate 40 Outer surface 42 Inner surface 42 52 First connecting member 54 Second connecting member 56 Rotating member 67 Fastening bolt 74 Rubber bushing 86 Spring member S Clearance reducing member P Circulation path

Claims (4)

A noise prevention structure for a chain that is circulated between a driving sprocket and a driven sprocket,
The chain portion is brought into contact with the chain portion from the outside of the circulation path so as to apply an inward tension of the circulation path to the chain portion located downstream of the driving sprocket and upstream of the driven sprocket. A first guide member that
A second guide member that abuts the chain portion from the inside of the circulation path so as to sandwich the chain portion with the first guide member and exert an outward tension of the circulation path on the chain portion;
A chain noise prevention structure characterized by comprising   In the second guide member, the chain contact start point of the second guide member is located downstream of the chain disengagement point of the drive side sprocket and upstream of the chain contact start point of the first guide member. The chain noise prevention structure according to claim 1, wherein the chain noise prevention structure is arranged as described above.   The second guide member is disposed such that a chain portion between the chain disengagement point of the driving side sprocket and a chain contact end point of the first guide member is curved in an S shape. The chain noise prevention structure according to claim 2. The chain is configured by alternately connecting inner links and outer links,
A clearance for reducing a clearance between the inner link plate and the outer link plate in at least one of the outer surface of the inner link plate of the inner link and the inner surface of the outer link plate of the outer link facing the outer surface. 4. The noise prevention structure for a chain according to claim 1, further comprising a reduction member.

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