JP2020197223A - sprocket - Google Patents

Abstract

To provide a sprocket capable of securing smooth driving of a roller chain, and suppressing occurrence of collision noise in meshing with a roller chain.SOLUTION: A sprocket 11 is configured such that link plates adjacent to each other in a series direction among a plurality of link plates 16 and 17 arranged in series are rotatably connected via a connection pin 19, and the outer periphery of the connection pin is provided with a plurality of tooth parts 12 that mesh with rollers 13A, 13B of a roller chain 14 when the roller chain is wound and rotated, the rollers rotatably fitted into the roller chain, wherein a pressure angle θ of the tooth part is set within a range of 4 degrees to 10 degrees.SELECTED DRAWING: Figure 3

Description

The present invention relates to a sprocket that rotates around a chain.

Conventionally, as a sprocket that suppresses a collision noise generated when a tooth portion provided on the outer periphery of a sprocket that rotates around a roller chain and a roller of a roller chain mesh with each other, for example, the sprocket described in Patent Document 1 has been used. Are known. In the sprocket described in Patent Document 1, the distance between the tooth surfaces of the tooth portions adjacent to each other in the circumferential direction is made smaller than the diameter of the roller that meshes between the tooth surfaces, so that the roller is engaged with the tooth portion at the time of meshing. It is designed so that it does not collide with the tooth bottom between the tooth and the tooth.

Jikkenhei 5-19720

However, at the time of meshing, even if the roller does not collide with the tooth bottom, it always hits the tooth surface between the tooth tip and the tooth bottom from an oblique direction, so that a collision sound is always generated. In addition, if the distance between the tooth surfaces of adjacent tooth parts in the circumferential direction is smaller than the diameter of the roller, it becomes difficult for the roller to come off from the state of being sandwiched between the tooth surfaces during meshing, and the chain can be driven smoothly. It may be hindered.

The present invention has been made in view of such circumstances, and an object of the present invention is a sprocket capable of suppressing the generation of collision noise at the time of meshing with the roller chain while ensuring smooth driving of the roller chain. Is to provide.

Hereinafter, means for solving the above problems and their actions and effects will be described.
In the sprocket that solves the above problems, the link plates that are adjacent to each other in the series direction in a plurality of link plates arranged in series are rotatably connected to each other via a connecting pin, and a roller is rotatable to the connecting pin. A sprocket in which a plurality of tooth portions that mesh with the rollers of the roller chain when the roller chain fitted to the roller chain is wound and rotated is provided on the outer periphery, and the pressure angle of the tooth portions is 4 degrees to 10 degrees. It is set in the range of degrees.

Here, the relative approach speed between the roller and the tooth when the roller of the roller chain approaches the tooth surface of the tooth portion of the sprocket from an oblique direction during meshing is V, and the pressure angle of the tooth portion of the sprocket is θ. Assuming that the speed at which the roller hits the tooth surface of the tooth portion at the time of meshing is VA, VA = V · sinθ. Therefore, the loudness of the collision sound generated when the roller hits the tooth surface of the tooth portion at the time of meshing is smaller when the pressure angle is relatively small than when the pressure angle is relatively large. However, if the pressure angle is less than 4 degrees, it becomes difficult for the rollers to come off from the state where the rollers are sandwiched between the tooth surfaces of the adjacent teeth in the circumferential direction of the sprocket when the sprocket is disengaged, and the roller chain can be driven smoothly. It may be hindered. On the other hand, when the pressure angle exceeds 10 degrees, the collision sound cannot be expected to decrease at the time of meshing, and it cannot be said that the generation of the collision sound can be suppressed. In this regard, according to the above configuration, since the pressure angle is set in the range of 4 to 10 degrees, the roller is removed from the state where the roller is sandwiched between the tooth surfaces of the tooth portions adjacent to each other in the circumferential direction at the time of disengagement. There is no rattling, and the speed at which the roller hits the tooth surface of the tooth portion at the time of meshing is reduced, so that the generation of collision noise can be suppressed.

In the sprocket, the diameter of the root circle passing through the tooth bases of the plurality of teeth may be smaller than the value obtained by subtracting the diameter of the roller from the pitch circle diameter of the pitch circles in the plurality of teeth. preferable.

Generally, the diameter of the base circle of the tooth of the sprocket is equal to the diameter of the pitch circle of the tooth minus the diameter of the roller. Therefore, when the roller of the roller chain is engaged with the tooth portion of the sprocket, the roller of the roller chain approaches the tooth surface of the tooth portion from an oblique direction and at the same time collides with the tooth bottom to generate a collision sound. In this respect, according to the above configuration, the tooth bottom circle diameter is set to be smaller than the value obtained by subtracting the roller diameter from the pitch circle diameter. Therefore, the roller of the roller chain does not collide with the tooth bottom when it hits the tooth surface of the tooth portion from an oblique direction at the time of meshing. Therefore, at the time of meshing, it is possible to suppress the generation of collision noise due to the rollers simultaneously hit the tooth surface of the tooth portion and the tooth bottom between the adjacent tooth portions in the circumferential direction.

In the sprocket, it is preferable that a groove having an opening width in the circumferential direction of the sprocket larger than the diameter of the roller is formed on the tooth bottom of the tooth portion.
According to this configuration, even if the roller falls into the tooth bottom during meshing, the tooth bottom has a groove having an opening width larger than the diameter of the roller, so that the roller can be applied to the tooth bottom having such a groove. The risk of being pinched can be reduced, and the smooth drive of the roller chain can be ensured.

In the sprocket, the axial end surface of the sprocket is attached to the link plate of the roller chain when the roller is displaced toward the tooth bottom due to the rotation of the sprocket when engaging with the tooth portion. It is preferable that a collision regulating member capable of restricting the roller from colliding with the tooth bottom is provided by abutting from the inside of the sprocket in the radial direction.

According to this configuration, when the roller is displaced toward the tooth bottom due to the rotation of the sprocket during meshing with the tooth portion, the link plate moves in the radial direction of the sprocket with respect to the collision regulating member before the roller collides with the tooth bottom. Contact from the outside of. Therefore, it is possible to prevent the roller from colliding with the tooth bottom, and it is possible to suppress the generation of collision noise due to the roller hitting the tooth bottom during meshing.

In the sprocket, when the roller comes into contact with the tooth surface of the tooth portion at the time of meshing with the tooth portion, the link plate and the collision regulating member are separated from each other by a first distance in the radial direction. It is preferable that the roller and the tooth bottom are separated by a second distance larger than the first distance in the radial direction.

According to this configuration, when the roller comes into contact with the tooth surface at the time of meshing with the tooth portion, the link plate does not abut against the collision regulating member, so that the collision noise between the link plate and the collision regulating member at this time is heard. Occurrence can be suppressed. Then, after that, as the sprocket rotates, the link plate gently abuts against the collision regulating member before the roller is about to collide with the tooth bottom, so that the link plate collides with the link plate at the time of such contact. The generation of collision noise with the member can also be suppressed.

According to the present invention, it is possible to suppress the generation of noise at the time of meshing with the roller chain while ensuring the smooth drive of the roller chain.

The front view of the state where the chain is wound around the sprocket of one embodiment. FIG. 2 is a cross-sectional view taken along the line 2-2 in FIG. Enlarged front view of the main part of the sprocket when the rollers start meshing with the teeth. Enlarged front view of the main part of the rotating sprocket with the rollers engaged with the teeth. An enlarged front view of a main part of the sprocket that is further rotating from the state of FIG. Enlarged front view of the main part of the sprocket when the roller finishes meshing with the tooth part.

Hereinafter, an embodiment of a sprocket that rotates around a chain will be described with reference to the drawings.
As shown in FIG. 1, the sprocket 11 is a rotating body in which a plurality of tooth portions 12 are formed at equal intervals on the outer periphery thereof, and a roller chain 14 having a roller 13 that meshes with the tooth portions 12 is wound around the sprocket 11. In this state, the roller chain 14 is configured to rotate about the axis 15 along the width direction orthogonal to the length direction (direction orthogonal to the paper surface of FIG. 1). The roller chain 14 has a plurality of pairs of inner link plates 16 that are separated from each other in the width direction and face each other, and a plurality of pairs of outer links that are arranged so as to sandwich each pair of inner link plates 16 from both outer sides in the width direction. It includes a plate 17. The inner link plate 16 and the outer link plate 17 are substantially rectangular plate-shaped members extending along the length direction of the roller chain 14, and their ends are alternately positioned in the length direction of the roller chain 14. They are arranged in series so that they overlap.

Cylindrical bushes 18 are assembled between the ends of each pair of the opposing inner link plates 16 in the length direction so as to maintain a space between the opposite inner link plates 16 in the width direction. On the other hand, between the ends of each pair of the outer link plates 17 facing each other in the length direction, a substantially columnar connecting pin 19 rotatably inserted into the bush 18 is provided between the outer link plates 17 facing each other. It is assembled so as to keep the space in the width direction. Then, via the connecting pin 19, as shown in FIG. 1, the inner link plate 16 and the outer link plate 17 are rotatably connected to each other at the ends adjacent to each other in the length direction of the roller chain 14. ing. In the case of the present embodiment, the cylindrical roller 13 in the roller chain 14 is rotatably fitted to the connecting pin 19 via the bush 18 (supported in a so-called loose fitting state).

As shown in FIGS. 1 and 2, disks 20 made of, for example, an elastic material or a metal material are arranged on both sides of the sprocket 11 in the axial direction so as to be in contact with the end face of the sprocket 11 in a coaxial arrangement with the sprocket 11. There is. The disk 20 is a circular plate material having a thickness larger than that of the link plates 16 and 17 in the roller chain 14, and is integrated with the sprocket 11 by fastening members 21 made of bolts and nuts at a plurality of locations in the circumferential direction thereof. It is fastened and fixed so that it rotates. The disk 20 has a sprocket on the end face of each of the link plates 16 and 17 in the longitudinal direction while the roller chain 14 is rotating around the sprocket 11 with the roller 13 meshed with the tooth portion 12 of the sprocket 11. Its diameter is set so that it can abut from the inside in the radial direction of 11.

As shown in FIGS. 1 and 3, each tooth portion 12 of the sprocket 11 has a first tooth surface 22 on the front side in the rotation direction (counterclockwise direction in this case) indicated by the solid arrow in FIG. The second tooth surface 23 is provided on the rear side in the rotation direction. The first tooth surface 22 is a surface that comes into contact with the roller 13 from the rear side in the rotation direction when the roller chain 14 is orbitably moved with the rotation of the sprocket 11, and the pitch circle 24 is formed in the height direction of the tooth portion 12. A certain region straddling the intersecting position in the radial direction forms a flat surface. The second tooth surface 23 also has a flat region that straddles the position intersecting the pitch circle 24 in the height direction of the tooth portion 12 in the radial direction, and the sprocket 11 is in the clockwise direction in FIG. In the case of rotation, the surface abuts on the roller 13 from the rear side in the rotation direction instead of the first tooth surface 22.

At the tooth bottom 25 between the first tooth surface 22 and the second tooth surface 23 of the tooth portions 12 adjacent to each other in the circumferential direction of the sprocket 11, the opening width W in the circumferential direction of the sprocket 11 is larger than the diameter DR of the roller 13. A large groove 26 is formed. Therefore, the roller 13 of the roller chain 14 is not sandwiched between the first tooth surface 22 and the second tooth surface 23 of the tooth portions 12 adjacent to each other in the circumferential direction when meshing with the tooth portion 12. Further, the root circle diameter DB of the root circle 27 passing through each of the tooth bases 25 of the plurality of tooth portions 12 of the sprocket 11 is from the pitch circle diameter DP of the pitch circle 24 of the plurality of tooth portions 12 of the sprocket 11 to the roller 13. It is smaller than the value obtained by subtracting the diameter DR.

Next, the action of the sprocket 11 configured as described above will be described by focusing on the meshing action of the roller 13 of the roller chain 14 with respect to the tooth portion 12 of the sprocket 11.
In the following, among the plurality of pairs of link plates 16 and 17 arranged in series in the roller chain 14, the pair of outer link plates 17 located at the uppermost position in FIG. 1 is located at the front end of the roller chain 14 in the traveling direction. The leading roller 13A located and the trailing roller 13B located at the rear end are referred to as the rollers 13 to be explained. Then, as the sprocket 11 rotates, the leading roller 13A and the trailing roller 13B, which are located one pitch P apart in the length direction of the outer link plate 17 to be explained, start meshing with the tooth portion 12. The state until the end of meshing will be described with reference to the drawings.

When the sprocket 11 rotates by half a pitch P in the rotation direction indicated by the solid arrow from the state shown in FIG. 1, the roller chain 14 causes a string vibration in the vertical direction in FIG. 1, which is called a cordal action. That is, the horizontal portion extending from the outer link plate 17 to be explained to the upstream side (right side in FIG. 1) of the roller chain 14 in the traveling direction maintains a horizontal posture together with the outer link plate 17, and is left in FIG. Displace diagonally forward and downward with the direction forward in the direction of travel.

Then, as shown in FIG. 3, the outer link plate 17 to be explained moves in a direction in which the central axis RC of the leading roller 13A moves diagonally forward and downward by half a pitch P in the rotation direction of the sprocket 11 on the pitch circle 24. Therefore, the following roller 13B also moves diagonally forward and downward from the position shown in FIG. 1 to the position shown in FIG. Then, with respect to the trailing roller 13B that has moved in this way, the tooth portion 12, which was located diagonally backward and downward in FIG. 1 with respect to the trailing roller 13B, moves diagonally forward and upward along the pitch circle 24. As shown in 3, the first tooth surface 22 of the tooth portion 12 is brought into contact with the rear side in the rotation direction. As a result, in the outer link plate 17 to be explained, the succeeding roller 13B starts meshing with the rear tooth portion 12, and both the leading roller 13A and the succeeding roller 13B are the first of the rear tooth portions 12, respectively. It is in a meshed state in which the tooth surface 22 is in contact with the contact CP.

Here, the trailing roller 13B to be explained approaches the first tooth surface 22 of the tooth portion 12 on the rear side from diagonally above and forward at the time of meshing. Then, in this case, the relative approach speed between the succeeding roller 13B and the tooth portion 12 is V, the pressure angle of the tooth portion 12 of the sprocket 11 is θ, and the succeeding roller 13B hits the first tooth surface 22 of the tooth portion 12 at the time of meshing. Assuming that the speed is VA, VA = V · sinθ. Therefore, at the time of meshing, the trailing roller 13B hits the first tooth surface 22 of the tooth portion 12 to generate a collision sound, but the loudness of the collision sound is such that the pressure angle θ is larger than that when the pressure angle θ is relatively large. It is considered that the case where it is relatively small is smaller. By the way, JIS B1812 (hereinafter referred to as "JIS standard") of Japanese Industrial Standards stipulates that the pressure angle is "the angle from the tooth profile pitch center line and the roller center acting at right angles to the roller contact surface." ing. For reference, when the pressure angle expressed by the JIS standard is shown in FIG. 3, the pressure angle θ is the tooth profile pitch center line PL and the roller 13 which are also straight lines connecting the central axes RC of the preceding roller 13A and the following roller 13B. It is expressed as an angle formed by a straight line DL extending from the central axis RC of (13A, 13B) so as to be orthogonal to the first tooth surface 22 of the tooth portion 12.

However, when the pressure angle θ is set to less than 4 degrees in order to minimize the collision noise, the tooth portions adjacent to each other in the circumferential direction of the sprocket 11 when the rollers 13 (13A, 13B) are disengaged from the tooth portions 12. It becomes difficult for the rollers 13 (13B) to come off from the state where the rollers 13 (13B) are sandwiched between the first tooth surfaces 22 and the second tooth surfaces 23 of the 12 teeth, which may hinder the smooth drive of the roller chain 14. On the other hand, the pressure angle θ is set so that the rollers 13 (13A, 13B) are not sandwiched between the first tooth surface 22 and the second tooth surface 23 of the tooth portions 12 adjacent to each other in the circumferential direction. When the temperature is set to exceed 10 degrees, it cannot be expected that the collision sound of the rollers 13 (13A, 13B) with respect to the tooth portions 12 is reduced, and it cannot be said that the generation of the collision sound can be suppressed.

In this respect, in the present embodiment, the pressure angle θ of the tooth portion 12 of the sprocket 11 is set to 6 degrees, which is an example of the range, so as to be within the range of 4 degrees to 10 degrees. Therefore, when the rollers 13 (13A, 13B) are disengaged from the tooth portions 12, they are difficult to disengage from the state of being sandwiched between the first tooth surfaces 22 and the second tooth surfaces 23 of the tooth portions 12 adjacent to each other in the circumferential direction. There is no such thing. Further, at the time of meshing, the speed VA when the rollers 13 (13A, 13B) approach and hit the first tooth surface 22 of the tooth portion 12 is reduced, so that a loud collision noise is not generated.

Further, usually, the tooth bottom circle diameter DB of the tooth portion 12 of the sprocket 11 is equal to the value obtained by subtracting the diameter DR of the rollers 13 (13A, 13B) from the pitch circle diameter DP. Therefore, the rollers 13 (13A, 13B) of the roller chain 14 approach the first tooth surface 22 of the tooth portion 12 from an oblique direction when meshing with the tooth portion 12 of the sprocket 11, and at the same time, also hit the tooth bottom 25. Collide and generate a loud collision sound. In this respect, in the present embodiment, the tooth bottom circle diameter DB is set to be smaller than the value obtained by subtracting the diameter DR of the rollers 13 (13A, 13B) from the pitch circle diameter DP. Therefore, the rollers 13 (13A, 13B) of the roller chain 14 do not collide with the tooth bottom 25 even when they come into contact with the first tooth surface 22 of the tooth portion 12 from an oblique direction during meshing.

Further, as shown in FIG. 3, when the succeeding roller 13B comes into contact with the first tooth surface 22 at the time of meshing with the tooth portion 12, the outer link plate 17 and the disk 20 to be explained are in the radial direction. The first distance G1 is separated from each other. Therefore, when the succeeding roller 13B comes into contact with the first tooth surface 22 at the time of meshing with the tooth portion 12, the outer link plate 17 to be explained does not come into contact with the disk 20, and therefore, at this point, the outer link plate 17 And the disk 20 do not come into contact with each other to generate a collision sound. Incidentally, the leading roller 13A that has already been in contact with and meshed with the first tooth surface 22 of the corresponding rear tooth portion 12 at this time and the tooth bottom 25 of the rear tooth portion 12 are first in the radial direction. The second distance G2, which is larger than the distance G1, is separated from each other.

Next, as shown in FIG. 4, when the sprocket 11 is further rotated by 2.5 pitch P in the rotation direction indicated by the solid arrow in FIG. 1 from the state shown in FIG. 3, the leading roller 13A and the succeeding roller 13B are respectively rotated. Slides the first tooth surface 22 of the corresponding rear tooth portion 12 toward the tooth bottom 25 and displaces it toward the tooth bottom 25. That is, the central axes RC of the leading roller 13A and the trailing roller 13B are displaced radially inward from the pitch circle 24. In particular, in the case of the leading roller 13A, after sliding the first tooth surface 22 of the rear tooth portion 12 toward the tooth bottom 25, the sprocket 11 is displaced even toward the front side in the rotation direction, and the rear tooth portion 12 The first tooth surface 22 and the second tooth surface 23 of the front tooth portion 12 are separated from each other.

Therefore, if the distance between the first tooth surface 22 and the second tooth surface 23 of the tooth portions 12 adjacent to each other in the circumferential direction on the tooth bottom 25 side is equal to or less than the diameter DR of the rollers 13 (13A, 13B). In this case, the rollers 13 (13A, 13B) may be sandwiched between the first tooth surface 22 and the second tooth surface 23. In this respect, in the present embodiment, even when the roller 13 (13A, 13B) falls toward the tooth bottom 25 during meshing, the tooth bottom 25 has an opening width larger than the diameter DR of the roller 13 (13A, 13B). Since there is a groove portion 26 of W, the roller 13 (13A, 13B) is not caught in the tooth bottom 25.

At that time, the outer link plate 17 to be explained, which has the leading roller 13A and the trailing roller 13B at both ends, is also displaced inward in the radial direction of the sprocket 11. That is, the outer link plate 17 has an outer peripheral surface of the disk 20 so that the first distance G1 in the radial direction with the outer peripheral surface of the disk 20 at the time when the succeeding roller 13B starts meshing with the tooth portion 12 becomes zero. It abuts from the outside in the radial direction. The outer link plate 17 moves inward in the radial direction while moving in the front side in the rotation direction as the sprocket 11 rotates, so that the outer link plate 17 gently moves from diagonally above the rear side in the rotation direction with respect to the outer peripheral surface of the disk 20. Abut. Therefore, it is possible to suppress the generation of collision noise when the end surface of the outer link plate 17 in the longitudinal direction comes into contact with the outer peripheral surface of the disk 20.

Even when the outer link plate 17 abuts on the disk 20 with the first distance G1 at the start of meshing set to zero in this way, the leading roller 13A and the trailing roller 13B still have the tooth bottom at the start of meshing. Since the second distance G2, which is larger than the first distance G1 in the radial direction, is separated from the 25, the second distance G2 does not become zero and collides with the tooth bottom 25. In this respect, the disk 20 has the link plates 16 and 17 of the roller chain 14 when the rollers 13 (13A and 13B) are displaced toward the tooth bottom 25 due to the rotation of the sprocket 11 when the rollers 13 (13A and 13B) are engaged with the tooth portions 12. It is a member that functions as a collision regulating member that can regulate the roller 13 from colliding with the tooth bottom 25 by contacting the sprocket 11 from the inside in the radial direction.

Next, as shown in FIG. 5, when the sprocket 11 is further rotated by 2 pitches P in the rotation direction indicated by the solid arrow in FIG. 1 from the state shown in FIG. 4, the leading roller 13A and the succeeding roller 13B are respectively sprocket. It also displaces toward the front side in the rotation direction of 11. In this case, the central axis RC of the succeeding roller 13B is displaced radially inward with respect to the pitch circle 24, and the first tooth surface 22 of the rear tooth portion 12 is also the second tooth portion 12 on the front side. It is also separated from the tooth surface 23. On the other hand, the leading roller 13A is displaced outward in the radial direction so that the position of the central axis RC returns to the top of the pitch circle 24, and is rearward in the rotation direction with respect to the second tooth surface 23 of the front tooth portion 12. It will be in a state of contact from the side.

Next, as shown in FIG. 6, when the sprocket 11 is further rotated by 2 pitches P in the rotation direction indicated by the solid arrow in FIG. 1 from the state shown in FIG. 5, the succeeding roller 13B is moved to the position of its central axis RC. Is displaced outward in the radial direction so as to return to the top of the pitch circle 24, and is in contact with the second tooth surface 23 of the tooth portion 12 on the front side from the rear side in the rotation direction. On the other hand, the leading roller 13A is separated from the second tooth surface 23 of the front tooth portion 12 and is between the first tooth surface 22 and the second tooth surface 23 of the tooth portions 12 adjacent to each other in the circumferential direction. It is displaced outward in the radial direction from the tooth portion 12 and ends the meshing with the tooth portion 12.

According to the above embodiment, the following effects can be obtained.
(1) Since the pressure angle θ is set to 6 degrees within the range of 4 to 10 degrees, the roller 13 is sandwiched between the tooth surfaces 22 and 23 of the tooth portions 12 adjacent to each other in the circumferential direction when the teeth are disengaged. It does not become difficult to come off from the state, and the speed at which the roller 13 hits the first tooth surface 22 of the tooth portion 12 at the time of meshing is reduced, so that the generation of collision noise can be suppressed.

(2) The tooth bottom circle diameter DB is set to be smaller than the value obtained by subtracting the diameter DR of the roller 13 from the pitch circle diameter DP. Therefore, the roller 13 of the roller chain 14 does not collide with the tooth bottom 25 when it hits the first tooth surface 22 of the tooth portion 12 from an oblique direction at the time of meshing. Therefore, at the time of meshing, it is possible to suppress the generation of collision sound due to the roller 13 simultaneously hitting the first tooth surface 22 of the tooth portion 12 and the tooth bottom 25 between the tooth portions 12 adjacent to each other in the circumferential direction.

(3) Even if the roller 13 is depressed toward the tooth bottom 25 during meshing, the tooth bottom 25 has a groove 26 having an opening width W larger than the diameter DR of the roller 13, so that such a groove 26 is present. The possibility that the roller 13 is pinched by the tooth bottom 25 can be reduced, and the smooth drive of the roller chain 14 can be ensured.

(4) When the roller 13 is displaced toward the tooth bottom 25 due to the rotation of the sprocket 11 when meshing with the tooth portion 12, the roller 13 is rotatable before the roller 13 is about to collide with the tooth bottom 25. The link plates 16 and 17 connected by the connecting pins 19 supported by the sprocket 11 come into contact with the disc 20 functioning as the collision regulating member from the outside in the radial direction of the sprocket 11. Therefore, it is possible to prevent the roller 13 from colliding with the tooth bottom 25, and it is possible to suppress the generation of collision noise due to the roller 13 hitting the tooth bottom 25 during meshing.

(5) When the roller 13 comes into contact with the first tooth surface 22 at the time of meshing with the tooth portion 12, the link plates 16 and 17 do not come into contact with the disk 20 functioning as a collision regulating member. The generation of collision noise between the link plates 16 and 17 and the disc 20 can be suppressed. After that, as the sprocket 11 rotates, the link plates 16 and 17 gently come into contact with the disc 20 functioning as a collision regulating member before the roller 13 is about to collide with the tooth bottom 25. It is also possible to suppress the generation of collision noise between the link plates 16 and 17 and the disc 20 at the time of such contact.

In addition, this embodiment can be implemented by changing as follows. Further, the present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.

-The collision regulating member is not limited to the disk 20, and may be a ridge formed on the side surface of the sprocket 11 so as to form an annular shape with the axis center C of the sprocket 11 as the center.
The collision regulating member is not limited to the disk 20, and a plurality of collision regulating members are formed on the side surface of the sprocket 11 at equal intervals in the circumferential direction so as to have an annular arrangement centered on the axis center C of the sprocket 11. It may be a convex portion.

The cross-sectional shape of the groove 26 formed in the tooth bottom 25 may be a semicircular cross section as long as the opening width W of the groove 26 is larger than the diameter DR of the roller 13.
The diameter DB of the root circle 27 passing through the roots 25 of the plurality of tooth portions 12 is smaller than the value obtained by subtracting the diameter DR of the roller 13 from the pitch circle diameter DP of the pitch circle 24 in the plurality of tooth portions 12. If so, the groove 26 of the tooth bottom 25 may be omitted.

If a groove 26 having an opening width W larger than the diameter DR of the roller 13 is formed in the tooth bottom 25, the tooth bottom circle diameter DB is equal to the value obtained by subtracting the diameter DR of the roller 13 from the pitch circle diameter DP. May be good.

The pressure angle θ is not limited to 6 degrees in the embodiment as long as it is within the range of 4 degrees to 10 degrees, and is a value of 4 degrees or more and less than 6 degrees and more than 6 degrees and 10 degrees or less, for example, 5 degrees or 7 degrees. It may be.

11 ... Sprocket, 12 ... Tooth, 13 (13A, 13B) ... Roller, 14 ... Roller chain, 16 ... Inner link plate, 17 ... Outer link plate, 19 ... Connecting pin, 20 ... Disc (collision control member), 22 ... 1st tooth surface, 23 ... 2nd tooth surface, 24 ... pitch circle, 25 ... tooth bottom, 26 ... groove, 27 ... tooth bottom circle, G1 ... first distance, G2 ... second distance, RC ... central axis , Θ… Pressure angle.

Claims (5)

A roller chain in which the link plates adjacent to each other in the series direction in a plurality of link plates arranged in series are rotatably connected via a connecting pin and a roller is rotatably fitted to the connecting pin. A sprocket having a plurality of teeth that mesh with the rollers of the roller chain when it is wound and rotated.
A sprocket characterized in that the pressure angle of the tooth portion is set in the range of 4 degrees to 10 degrees. A claim characterized in that the diameter of the root circle passing through the tooth bases of the plurality of teeth is smaller than the value obtained by subtracting the diameter of the roller from the pitch circle diameter of the pitch circles in the plurality of teeth. Item 1. The sprocket according to item 1. The sprocket according to claim 1 or 2, wherein a groove having an opening width in the circumferential direction of the sprocket larger than the diameter of the roller is formed on the tooth bottom of the tooth portion. On the axial end face of the sprocket, with respect to the link plate of the roller chain when the roller is displaced toward the tooth bottom of the tooth portion due to rotation of the sprocket when engaging with the tooth portion. Any of claims 1 to 3, wherein a collision regulating member capable of restricting the roller from colliding with the tooth bottom by contacting the sprocket from the inside in the radial direction is provided. The sprocket described in item 1. At the time when the roller comes into contact with the tooth surface of the tooth portion at the time of meshing with the tooth portion, the link plate and the collision restricting member are separated by a first distance in the radial direction. The sprocket according to claim 4, wherein the roller and the tooth bottom are separated from each other by a second distance larger than the first distance in the radial direction.