JPH0721434Y2 - Multi-stage sprocket device for bicycle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a multi-stage sprocket device for a bicycle, more specifically, a bicycle crank or a sprocket having at least one large diameter sprocket and at least one small diameter sprocket. The present invention relates to a multi-stage sprocket device for a bicycle, which is mounted on a rear wheel hub to change gears by changing a drive chain.

(Prior Art) Conventionally, as this type of multi-stage sprocket device,
As described in Japanese Patent No. 617, a small-diameter sprocket and a large-diameter sprocket are combined such that one inter-tooth center of the large-diameter sprocket is located on the leader line in the tangential direction of the withdrawal from one inter-tooth center of the small-diameter sprocket. The interval between the centers of the teeth is an integer multiple of the chain pitch, and the first tooth facing the rear side of the center of the teeth in the drive rotation direction of the large-diameter sprocket is an easily meshing tooth and is larger than the small-diameter sprocket. It has been proposed that the gear change performance can be improved when the chain is engaged with a radial sprocket.

(Problems to be solved by the invention) However, in the above configuration, when the chain is changed from the small sprocket to the large sprocket, the chain is pressed to the large sprocket side. Since the chain contacts the inner surface of the sprocket on the side of the small diameter sprocket and the chain cannot be moved closer to the large sprocket, the chain roller rides on the specific tooth, and the chain roller that has been climbed up is the large diameter sprocket. As the drive rotation of the device advances, it falls into the tooth bottom and meshes in an impact, and the gear shifting performance is poor. Moreover, a loud noise, that is, a metallic sound is generated during the impact meshing, and In the multi-stage sprocket device, the stepping torque of the crank changes greatly.

The present invention was devised in view of the above problems, and an object thereof is to smoothly engage with a chain in relation to a chain pitch, and moreover, from a small diameter sprocket to a large diameter sprocket. When changing chains, the chain to be changed can be effectively brought closer to the outer side than the inner side of the small sprocket side of the large sprocket, and the chain is rearward in the drive rotation direction with respect to the center of the teeth on the large sprocket. It can mesh smoothly and effectively with the teeth facing the gears, and its shifting performance can be improved, and the chain can make a shocking noise and make a loud noise, and the stepping torque of the crank can change greatly. It is a point to provide a multi-stage sprocket device capable of eliminating the problem.

(Means for Solving the Problems) Then, the present invention is at least one large-diameter sprocket (1) having a large number of teeth circumferentially provided at the chain pitch of the drive chain, A multi-stage sprocket device comprising at least one small-diameter sprocket (2) having on its outer periphery teeth arranged at a chain pitch interval smaller than the large-diameter sprocket (1). Then, each sprocket (1) (2) is connected to one of the large sprocket (1) on a tangential lead line drawn from one interdental center (O ₁ ) of the small diameter sprocket (2). The combination is made so that the center of the tooth (O ₂ ) is positioned, and the distance between the centers of the teeth (O ₁ ) (O ₂ ) is an integer multiple of the chain pitch, while the large sprocket ( 1 In the smaller sprocket side inner side surface, and, on the moving track of when the interdental center (O ₁₎ (O ₂₎ between the drive chain is moved, the chain interferes located in large sprocket, the chain The entire outer shape including the link plate of the chain when the tooth starts to mesh with the tooth facing the rear side in the drive rotation direction with respect to the center of the tooth (O ₂ ) in the large diameter sprocket (1) away from the small diameter sprocket (2) The edge intervenes to provide a chain guide surface (12) having a size and shape which allows the large sprocket (1) to be offset to the large sprocket (1).

The chain guide surface (12) is recessed from the interdental center (O ₁ ) side to the interdental center (O ₂ ) side edge, and has the interdental center (O ₂ ) side recessed depth. Is the depth at which the teeth of the large-diameter sprocket (1) facing the rear side in the drive rotation direction with respect to the center (O ₂ ) of the inter-tooth space do not continue riding on the large-diameter sprocket-side inner link plate of the chain. Is preferred.

Further, the first tooth facing the rear side in the drive rotation direction with respect to the center (O ₂ ) between the teeth of the large diameter sprocket (1) is meshed when the chain is engaged with the small diameter sprocket (2) to the large diameter sprocket (1). It is preferable to use easy-to-engage teeth.

In addition, all the teeth except the at least two teeth including the first tooth facing the rear side in the drive rotation direction with respect to the center (O ₂ ) between the teeth of the large diameter sprocket (1) are changed from the small diameter sprocket (2) to the large diameter. It is preferable to use hard-to-engage teeth that are difficult to engage when the chain is engaged with the sprocket (1).

The chain guide surface (12) has a center (O ₁ ) between its teeth.
The side recess depth and the interdental center (O ₂ ) side recess depth may be different. In this case, it is preferable that the interdental center (O ₂ ) side indentation depth of the chain guide surface (12) be deeper in multiple steps than the interdental center (O ₁ ) side indentation depth.

Further, it is preferable that the teeth facing the chain guide surface (12) of the large-diameter sprocket (1) have a circumferential tooth width wider than the circumferential tooth width of the teeth excluding the teeth facing the chain guide surface.

In addition, in the present invention, "a distance of an integral multiple of the chain pitch" means, of course, that the distance between the centers of the teeth (O ₁ ) (O ₂ ) is the same as the interval of the integral multiple of the chain pitch. O ₁ )
This also includes the case where the interval of (O ₂ ) is made slightly smaller than the integer multiple of the chain pitch.

(Operation) In particular, when the chain is exchanged from the small diameter sprocket (2) to the large diameter sprocket (1), the chain can be smoothly run without riding on the teeth of the large diameter sprocket as compared with the conventionally known sprockets. In addition, the gears can be effectively meshed and the gear shifting performance can be improved. Furthermore, the chains can be meshed without riding on the large-diameter sprocket teeth. It is possible to eliminate the occurrence of a large change in the crank stepping torque.

That is, when changing the chain from the small diameter sprocket (2) to the large diameter sprocket (1), even if the chain is moved to the large diameter sprocket side at a position that does not match the chain pitch,
The chain does not ride on the large-diameter sprocket teeth and does not mesh with the large-diameter sprocket teeth, and the facing space between the outer link plates of the chain is located at a position corresponding to the chain pitch. ₂ ) It meshes with the teeth facing the rear side in the direction of drive rotation, but as in the previous example, the length between the center of the teeth (O ₁ ) (O ₂ ) is an integer multiple of the chain pitch. If you just do, the chain will contact the inner surface of the large sprocket and cannot move closer to the large sprocket any more, so the chain roller will ride on the specific tooth and the chain roller that has climbed will be large. As the driving rotation of the radial sprocket progresses, the sprocket falls to the bottom of the tooth and engages with each other in an impact, and a loud noise, that is, a metallic sound is generated at the time of the impact engagement. In the multi-stage front sprocket device when meshing, the stepping torque of the rackunk will change greatly, but in the present invention, the entire outer edge of the chain intervenes at a position that matches the chain pitch of the large diameter sprocket. By providing the chain guide surface (12) having a size and a shape that allows the large-diameter sprocket to be offset to one side, the chain is biased toward the outer surface side rather than the inner surface of the large-diameter sprocket (1). Although the other parts are not configured to shift, even if the chain is operated to shift to the large diameter sprocket in other parts, the gears do not originally mesh with each other. There is no effect on the deterioration of the property, and since the chain guide surface (12) having the above-mentioned configuration is provided at the portion matching the chain pitch, it is separated from the small diameter sprocket (2). A chain that meshes with the specific teeth of the large diameter sprocket (1) can be effectively moved toward the outer side with respect to the inner side surface of the large diameter sprocket (1) along the chain guide surface (12). As a result, the specific teeth smoothly intervene in the facing space portion without the rollers of the chain being biased up riding on the specific teeth of the large-diameter sprocket. The radial sprocket (1) can be smoothly and effectively meshed without being depressed due to the progress of driving rotation of the radial sprocket (1), and therefore, it is possible to obtain a shift that cannot be obtained by the reference example and other known sprockets. In other words, it is possible to improve the property, that is, the shiftability from the small diameter sprocket to the large diameter sprocket. Furthermore,
After adjusting the chain pitch, the chain guide surface (1
By providing 2), it is possible to engage the chain without riding on the teeth, so it is possible to prevent the chain from impacting and making noises, and the crank stepping torque does not change significantly. To get.

Further, the chain guide surface (12) is provided on the inner surface of the large diameter sprocket (1) on the small diameter sprocket side on the movement path when the chain moves between the center of the teeth (O ₁ ) (O ₂ ). In other words, in other words, since the chain guide surface (12) is not provided at a position where the chain pitch is not adjusted, the strength reduction of the large diameter sprocket (1) due to the chain guide surface (12) can be reduced. is there.

Further, since the pitch of the teeth provided on the outer periphery of each of the sprockets (1) and (2) is the chain pitch interval, there is no problem of so-called chain jump in which the teeth pass over the drive chain when the sprockets are driven and rotated. is there.

When the depth of the chain guide surface (12) is set so that the teeth do not continue to climb on the large diameter sprocket-side inner link plate in the chain, the inner link plate of the chain is attached to the teeth. Even if it corresponds, it is possible to prevent the inner link plate from getting on the teeth and not meshing well.

If the first tooth (11) facing the rear side in the drive rotation direction with respect to the center (O ₂ ) between the teeth of the large diameter sprocket (1) is an easily meshing tooth, the outer tooth of the chain is attached to this first tooth. When the plates are corresponding, the chain can be better meshed with the first teeth.

Further, when all the teeth except the at least two teeth including the first tooth (11) facing the rear side in the drive rotation direction with respect to the center of the teeth of the large-diameter sprocket (1) are difficult-to-mate teeth,
Reduce the chain re-engagement at other than the characteristic position where the distance between the center of the teeth (O ₁ ) (O ₂ ) is an integer multiple of the chain pitch, or
Alternatively, it is possible to perform the chain changing at the specific position while concentrating the chain changing at the specific position. That is, even when the inner link plate of the chain corresponds to the first tooth (11), in particular, the outer link plate of the chain corresponding to the second tooth adjacent to the first tooth (11) is The teeth can be satisfactorily meshed with each other, and the shifting performance can be further improved.

Further, the strength of the large diameter sprocket (1) can be improved by making the recess depth of the chain guide surface (12) closer to the center of the tooth (O ₁ ) and the recess depth of the middle of the tooth (O ₂ ) side. The chain guide surface (12) can be provided according to the movement trajectory of the chain without lowering it.

In addition, when the recess depth of the chain guide surface (12) on the center of the tooth (O ₂ ) side is made deeper stepwise than the recess depth of the middle of the tooth (O ₁ ) side, the depth is inclined. The large-diameter sprocket (1) can be molded more easily than the case where the chain is made different, and the position of the chain can be determined at a plurality of positions by contacting the step-moving chain with each step surface. The outer link plate of the chain is the first tooth (11)
This chain can be more favorably meshed with the first tooth (11), the depth can be easily measured with a measuring tool such as a dial gauge, and the large diameter sprocket (1) can be used. When molding, the chain guide surface (1
The teeth facing 2) can be formed less susceptible to the directionality of the metal structure.

Further, the chain guiding surface (12) of the large-diameter sprocket (1) has a circumferential width which is wider than the circumferential width of the teeth excluding the teeth facing the chain guiding surface. It is possible to reduce the decrease in strength due to the provision of the 1-chain guide surface of the tooth facing the (12).

(Example) The multi-stage sprocket device of the present invention may be mounted on a crank of a bicycle or mounted on a rear wheel hub.

The one shown in the figure is to be mounted on the rear wheel hub of the bicycle, and has one large sprocket (1) with a large number of teeth around the outer periphery of the drive chain (3) at the chain pitch.
And the outer circumference of the large-diameter sprocket (1) has teeth arranged around the chain pitch with a smaller number of teeth.
It comprises a small diameter sprocket (2), and these sprockets (1) and (2) are attached to a drive member (not shown) at predetermined intervals in the axial direction, and the drive member is mounted on the rear wheel via a bearing. It is rotatably supported by the driven member of the hub.

Therefore, in the embodiment shown in the drawings, each sprocket (1) (2) has a large diameter on the tangential lead line drawn from one interdental center (O ₁ ) of the small diameter sprocket (2). The sprocket (1) is assembled so that one center (O ₂ ) between the teeth is positioned, and the distance (L) between the centers (O ₁ ) (O ₂ ) between the teeth is an integer multiple of the chain pitch. On the other hand, when the chain (3) moves on the inner surface (1a) of the large-diameter sprocket (1) on the small-diameter sprocket side and between the interdental centers (O ₁ ) (O ₂ ). On the locus, at a position where the chain (3) interferes with the large diameter sprocket (1), the chain (3) is separated from the small diameter sprocket (2) and the large diameter sprocket (1).
The outer edge portion including the link plate of the chain (3) intervenes mainly when engaging with the first tooth (11) facing the rear side in the drive rotation direction with respect to the interdental center (O ₂ ) in A chain guide surface (12) having a size and a shape that allows the large-diameter sprocket (1) to shift to one side is provided.

In the above structure, the chain guide surface (12) serves as a large-diameter sprocket-side outer link plate (31) of the chain (3) when the chain (3) starts to mesh with the first teeth (11). The second link is formed into a size and shape capable of receiving the entire outer peripheral edge portion on the large diameter sprocket side including the inner link plate (32) and the link pin (33).
As shown in the figure, the drive chain (3) can be moved toward the outer side surface (1b) by a predetermined amount with respect to the inner side surface (1a) of the large diameter sprocket, and the outer link plate (31) can be attached to the first tooth (11). When it corresponds, the wide space portion (3a) between the outer link plates (31) can be satisfactorily engaged with the first teeth (11).

In addition, the chain guide surface (12) has the interdental center (O ₁ ).
From the side toward the interdental center (O ₂ ) side edge, and the interdental center (O ₂ ) side recess depth is set to the first tooth (1
1) The inner link in the drive chain in which the small-diameter sprocket (2) is changed to the large-diameter sprocket (1) as a depth at which the large-diameter sprocket-side inner link plate (32) in the chain (3) does not continue to climb up and down. When the plate (32) is in a position corresponding to the first tooth (11), it is possible to prevent the large diameter sprocket side inner link plate (32) from riding on the first tooth (11) as shown in FIG. Also, even if you get on the train, you can prevent the ride from continuing.

Further, the guide surface (12) is located at a position (A) in which the starting end on the inter-tooth center (O ₁ ) side is displaced forward from the inter-tooth center (O ₂ ) in the drive rotation direction by twice the chain pitch (A). When the outer link plate (31) of the drive chain (3) is located at a position corresponding to the first tooth (11) as the position displaced toward the center (O ₂ ) side between the teeth, as shown in FIG. Two adjacent link pitch (33) edges of the drive chain (3) come into contact with the position A) and the middle portion of the chain guide surface (12), and one of the link pins (33) and the large diameter sprocket side. Outer link plate (31) and inner link plate (32)
And the drive chain (3) by interposing on the chain guide surface (12)
Can be brought closer to the outer surface (1b) side.
Also, the inner link plate (32) of the drive chain (3)
Is located at a position corresponding to the first tooth (11), one edge of the link pin (33) abuts at the position (A) as shown in FIG. 3, and the side surface of the outer link plate (31) is located at the side. The link pin (33) and the outer link plate (31) intervene in the chain guide surface (12) by abutting the starting end of the chain guide surface (12), and the drive chain (3) is moved to the outer surface (1b). ) Can be brought to the side. In addition, the portion between the pin holes of the outer link plate (31) is outwardly bulged to the extent of the protrusion length of the ink pin (33) with respect to the outer link plate (31) so that the end face of the link pin (33) is a sprocket. In the case of a drive chain in which it is difficult to contact the side surface, the outer link plate (instead of the end surface of the link pin (33) abutting at the position (A) and the intermediate portion of the chain guide surface (12). The outer surface of the bulging part of 31) comes into contact.

Further, the chain guide surface (12) has a depth from the end side, more specifically, a depth from the position where the link pin (33) adjacent to the position (A) abuts the link pin to the end edge (the sixth edge).
(See the drawing) is deeper than the depth of the starting end side (see FIG. 5) (see FIG. 7) so that the strength reduction of the large diameter sprocket due to the provision of the chain guide surface (12) is eliminated. In addition, when changing the depth of the chain guide surface (12),
In addition to changing stepwise as shown in FIGS. 7 to 7, it may be changed by inclining. However, when the depth is increased stepwise, it is easier to mold the large diameter sprocket (1) than when the depth is made different by tilting, and the drive chain is brought into contact with each step surface. Since the position of the drive chain can be determined in a plurality of positions, when the outer link plate (31) of the chain corresponds to the first tooth (11), the chain is better meshed with the first tooth (11). In addition, the depth can be easily measured with a measuring tool such as a dial gauge, and the teeth facing the chain guide surface (12) can be oriented in the metallographic structure when the large diameter sprocket (1) is molded. There is an advantage that molding is less likely to be affected by.

Further, a step portion (13) is provided between the center side edge of the large diameter sprocket of the chain guide surface (12) and the inner side surface (1a) as shown in FIGS. The outer link plate (31) of the drive chain guided by the outer link plate (3) is received by the step (13).
It is possible to prevent the chain from sliding down from the chain guide surface (12) toward the center of the large diameter sprocket before the wide space portion (3a) between 1) meshes with the first tooth (11).

Further, since the tooth thickness of the tooth facing the chain guide surface (12) is thin by the depth corresponding to the guide surface, the tooth width in the circumferential direction is set to the tooth width in the circumferential direction as shown in FIGS. It is preferable to make it wider than the tooth width to reduce the strength reduction.

Further, it is preferable that the first tooth (11) is an easily meshing tooth that is easily meshed when the chain is changed from the small diameter sprocket (2) to the large diameter sprocket (1). In this case, for example, as shown in FIG. 2, the sprocket is inclined rearward with respect to the center line between the inner surface and the outer surface of the large diameter sprocket in the direction opposite to the small diameter sprocket.

Further, all the teeth except at least two teeth including the first tooth (11) facing the rear side in the drive rotation direction with respect to the center (O ₂ ) between the teeth of the large diameter sprocket (1) are shown in FIGS. As shown, the teeth are hard to mesh when the chain is changed from the small diameter sprocket (2) to the large diameter sprocket (1). This difficult meshing tooth chamfers the inner surface of the tooth on the small diameter sprocket side as shown in FIG. 2, or drives it to the center line between one side and the other side in the thickness direction of the sprocket body as shown in FIG. The small-diameter sprocket (2) is inclined toward the front in the rotation direction to the side opposite to the small-diameter sprocket (2).
Therefore, it is difficult to mesh with the drive chain that is engaged with the large diameter sprocket (1).

It is to be noted that at least the first tooth (11) and the second tooth (14) adjacent to the rear side of the first tooth (11) in the driving rotation direction are not difficultly meshed teeth because the outer link plate ( 31) is at a position corresponding to the first tooth (11),
The narrow space portion (3b) between the inner link plates (32) adjacent to the rear of the outer link plate (31) in the drive rotation direction is easily accommodated in the second teeth (14), and the inner link plate of the drive chain is also provided. (32) is the first tooth (1
When it is in a position corresponding to 1), the wide space part (3a) between the outer link plates (31) adjacent to the rear of the inner link plate (32) in the drive rotation direction meshes with the second teeth (14). To do so. The third tooth (15) adjacent to the rear side of the second tooth (14) in the drive rotation direction.
Even if the outer link plate (31) is in a position corresponding to the second tooth (14),
It is preferable that the narrow space portion (3b) between the inner link plates (32) adjacent to the rear side of the outer link plate (31) in the drive rotation direction is easily accommodated in the third teeth (15).

Further, the inter-tooth length (l) in the pitch circle portion of the teeth of the small diameter sprocket (2) and the teeth of the large diameter sprocket (1)
Is formed to be longer than the outer diameter of the roller in the chain by a predetermined length. Therefore, the center of each tooth (O ₁ )
The interval (L) of (O ₂ ) is smaller than the integer multiple interval of the chain pitch. That is, when each sprocket is mounted on the rear wheel hub, the driving force due to the depression of the pedal is transmitted from the drive chain to the sprocket (1) or (2), so that the small sprocket (2) to the large sprocket (2). When the chain is switched to 1), the roller on the small diameter sprocket side of the drive chain contacts the rear surface of the tooth on the front side in the drive rotation direction with respect to the roller as shown in FIG. 1, and also on the large diameter sprocket (1) side. The roller of the drive chain, which shifts to and is caught by the large-diameter sprocket tooth, comes into contact with the front surface of the first tooth (11) on the front side in the drive rotation direction, so that the sprockets (1) and (2) are aligned with each other. In this case, the interval (L) between the centers (O ₁ ) (O ₂ ) of the interdental teeth is slightly shorter than the integer multiple interval of the chain pitch. If the inter-tooth length in the pitch circle portion of the teeth of each sprocket (1) and (2) corresponds to the outer diameter of the roller, the interval (L) is an integer multiple of the chain pitch. To do.

Next, when the drive chain is changed over by the derailleur, the meshing relationship between the chain and the sprockets (1) and (2) will be described with reference to FIGS.

1 to 3, the movable member of the rear derailleur is moved in the direction of arrow F in FIGS. 2 and 3 to drive the small chain sprocket (2) to the large chain sprocket (1). When the drive chain (3) meshing with the teeth of the small-diameter sprocket (2) is displaced by the rear derailleur in the state in which the sprocket (3) is reengaged, the front side of the sprocket (1) (2) in the rotation direction (arrow). The drive chain located in the (X direction) remains on the small sprocket (2), and the drive chain located on the operating side of the rear derailleur reaches the side of the large sprocket (1) and tilts as shown in FIG. 2 or 3. Then, the large sprocket (1) is pressed.

In addition, when changing the chain from the small diameter sprocket (2) to the large diameter sprocket (1), the drive chain (3) moves between the inter-tooth centers (O ₁ ) (O ₂ ) aligned with an integer multiple of the chain pitch. a of being carried out by moving, interdental center (O ₁₎ (O ₂₎ spacing between have to conform to an integral multiple spacing of the chain pitch, moreover, the interdental center (O ₁₎ (O ₂ ) Is provided with a chain guide surface (12) at a position corresponding to the movement trajectory of the chain between the two, so that the drive chain (1) is allowed to shift to one side. 3) when the chain (3) starts to mesh with the first tooth (11) facing away from the center of the tooth (O ₂ ) in the large-diameter sprocket (1) in the driving rotation direction away from the small-diameter sprocket (2). The wide space (3a) between the outer link plates (31) of the Located opposite the teeth (11), it has no other interference with the roller in driving chain (3).

Therefore, as the large-diameter sprocket (1) is driven and rotated, the roller is not lifted up by the first tooth (11) and is not lifted, and the first tooth (11) is located between the outer link plates (31). Since it intervenes in the wide space portion (3a), the lifted drive chain can be smoothly meshed with each other without impacting the large-diameter sprocket (1) as the driving rotation of the large-diameter sprocket (1) is lowered. You can do it.

Moreover, the chain guide surface (12) is provided at a specific position where the distance between the centers of the teeth (O ₁ ) (O ₂ ) is an integer multiple of the chain pitch, and the size and size of the chain guide surface (12) The outer edge including the link plate of the chain (3) intervenes when the shape begins to mesh mainly with the first tooth (11) facing the rear side in the drive rotation direction with respect to the interdental center (O ₂ ). Since the size and the shape allow the deviation to the large diameter sprocket (1), when changing the chain from the small diameter sprocket (2) to the large diameter sprocket (1),
The entire outer edges of the link pin (33) of the chain (3) and the large-diameter sprocket-side outer link plate (31) and inner link plate (32) intervene in the chain guide surface (12). When the drive chain (3) is moved toward the large diameter sprocket (1) by the chain guide surface (12), the center of the teeth (O ₁ ) (O ₂ ) is moved. It is possible to effectively engage the drive chain (3) that moves the (1) with the teeth of the large diameter sprocket (1) without any mistake. That is, when the outer link plate (31) of the drive chain (3) corresponds to the first tooth (11), the outer link plate (31) does not get on or off the first tooth (11). It can be effectively engaged without falling.

Further, since the pitch of the teeth provided on the outer circumference of each of the sprockets (1) and (2) is a chain pitch interval, there is a problem of so-called chain jump in which the teeth pass over the drive chain (3) when the sprockets are driven and rotated. It does not happen.

In the chain guided by the chain guide surface (12), the outer link plate (31) contacts the step (13),
It is possible to prevent the chain guide surface (12) from sliding down to the center side of the large-diameter sprocket, so that the first teeth (11) can be meshed more favorably.

Further, the chain guide surface (12) has the recess depth on the side of the inter-tooth center (O ₂ ) to the first tooth (11) of the large diameter sprocket side inner link plate (32) in the drive chain (3). The inner link plate (32) of the drive chain (3) for changing from the small diameter sprocket (2) to the large diameter sprocket (1) corresponds to the first tooth (11) because the depth is such that the riding of the In the position, as shown in FIG. 3, the outer link plate (31) comes into contact with the terminal end portion of the chain guide surface (12), and the large diameter sprocket-side inner link plate (corresponding to the first tooth (11) ( 32) can be prevented from riding on the first tooth (11), and even when riding,
The inner link plate (3
Wide space part (3a) adjacent to narrow space part (3b) between 2)
Can be prevented from not meshing well with the second tooth (14).

Further, by making all the teeth other than the first tooth (11) and the second tooth (14) difficult to mesh, the inner link plate (32) of the chain becomes the first tooth (11). When in the corresponding position, the outer link plate (31) adjacent to the inner link plate (32) rearward in the drive rotation direction.
The wide space portion (3a) therebetween can be meshed with the second tooth (14).

In the above embodiments, the case where two sprockets are combined has been described, but other three or more sprockets may be combined, and the sprockets may be used for the rear wheel hub and the crank. Of.

(Effect of the Invention) As described above, according to the present invention, particularly when the chain is changed from the small diameter sprocket (2) to the large diameter sprocket (1),
Compared with each conventionally known sprocket, the chain can be engaged smoothly and effectively without riding on the teeth of the large-diameter sprocket, and its gear shifting performance can be improved. Since the meshing can be performed without riding on the radial sprocket tooth, it is possible to prevent the chain from impacting and making a noise and making a large change in the stepping torque of the crank.

That is, when changing the chain from the small diameter sprocket (2) to the large diameter sprocket (1), even if the chain is moved to the large diameter sprocket side at a position that does not match the chain pitch,
The chain does not ride on the large-diameter sprocket teeth and does not mesh with the large-diameter sprocket teeth, and the space between the outer link plates of the chain at the location matching the chain pin is the center of the interdental space (O ₂ ) To the teeth facing the rear side in the drive rotation direction, the length between the centers of the teeth (O ₁ ) (O ₂ ) is set to an integral multiple of the chain pitch as in the above-mentioned conventional example. If you do so, the chain will come into contact with the inner surface of the large sprocket and cannot move closer to the large sprocket anymore, so the chain roller will ride on the specific tooth, and this chain roller As the drive rotation of the sprocket progresses, it falls into the tooth bottom and meshes with impact, and a loud noise, that is, a metallic sound is generated during this impactful meshing.
In the front multi-stage sprocket device at the time of the impact engagement, the stepping torque of the crank will change greatly.However, in the present invention, the entire chain of the chain is placed at a position corresponding to the chain pitch of the large diameter sprocket. The chain guide surface (12) having a size and a shape that allows the outer edge to intervene to shift toward the large diameter sprocket side is provided, and the chain is provided on the outer side surface rather than the inner side surface of the large diameter sprocket (1). Even if the chain is moved to the large diameter sprocket at other parts, it does not originally mesh with each other. Therefore, the reduction of the speed change is not affected, and the chain guide surface (12) having the above-mentioned structure is provided at the portion matching the chain pitch. A chain that engages with the specific tooth of the large diameter sprocket (1) apart from (2) is effectively moved along the chain guide surface (12) by a predetermined amount on the outer surface side with respect to the inner surface of the large diameter sprocket (1). The result is that the specific teeth smoothly intervene in the facing space portion without the rollers of the chain that have been offset to ride on the specific teeth of the large sprocket. It is possible to smoothly and effectively mesh the riding chain without engaging with the large sprocket (1) as the driving rotation of the large-diameter sprocket (1) falls, and thus to mesh with each other smoothly. It is possible to improve the speed change which cannot be obtained with the sprocket, that is, the speed change from the small diameter sprocket to the large diameter sprocket. Furthermore,
After adjusting the chain pitch, the chain guide surface (1
By providing 2), it is possible to engage the chain without riding on the teeth, so it is possible to prevent the chain from impacting and making noises, and the crank stepping torque does not change significantly. To get.

Further, the chain guide surface (12) is provided on the inner surface of the large diameter sprocket (1) on the small diameter sprocket side on the movement path when the chain moves between the center of the teeth (O ₁ ) (O ₂ ). In other words, in other words, since the chain guide surface (12) is not provided at a position where the chain pitch is not adjusted, the strength reduction of the large diameter sprocket (1) due to the chain guide surface (12) can be reduced. is there.

Further, since the pitch of the teeth provided on the outer periphery of each of the sprockets (1) and (2) is the chain pitch interval, there is no problem of so-called chain jump in which the teeth pass over the drive chain when the sprockets are driven and rotated. is there.

Further, when the depth of the chain guide surface (12) is set to a depth such that the large-diameter sprocket-side inner link plate of the chain does not continue to ride on the tooth, the inner link plate of the chain is attached to the tooth. Even if it corresponds, it is possible to prevent the inner link plate from getting on the teeth and not meshing well.

Further, the first tooth (11) facing the rear side in the drive rotation direction with respect to the center (O ₂ ) between the teeth of the large diameter sprocket (1) is made to be an easily meshing tooth, so that the first tooth (11) is driven. When the outer link plate of the chain corresponds, the chain can be better meshed with the first tooth (11).

In addition, all teeth except at least two teeth including the first tooth (11) facing the rear side in the drive rotation direction with respect to the center of the teeth of the large-diameter sprocket (1) are made to be teeth that are difficult to mesh with each other. While reducing or eliminating chain interchanging at a position other than the specific position where the distance between the centers (O ₁ ) (O ₂ ) is an integer multiple of the chain pitch, the chain interchanging can be concentrated at the specific position, It is possible to favorably change the chain at this specific position. That is, even when the inner link plate of the chain corresponds to the first tooth (11), in particular, the outer link plate of the chain corresponding to the second tooth adjacent to the first tooth (11) is The teeth can be satisfactorily meshed with each other, and the shifting performance can be further improved.

Further, by making the recess depth of the chain guide surface (12) on the center (O ₁ ) side between the teeth different from the recess depth of the center of the tooth (O ₂ ) side, the strength of the large diameter sprocket (1) is increased. It is possible to provide the chain guide surface (12) according to the movement trajectory of the chain without lowering the temperature.

When the depth of recess between the tooth guide surface (12) on the center of the tooth (O ₂ ) side is made deeper than the depth of recess between the center of the tooth (O ₁ ) on a stepwise basis, the depth is slanted. The outer sprocket (1) can be molded more easily than in the case where the chain is made different, and the chain position can be determined at a plurality of positions by bringing the chain into contact with each step surface. Corresponds to the first tooth (11), the chain can be more favorably engaged with the first tooth (11), and the depth can be easily measured by a measuring tool such as a dial gauge. Further, when forming the large-diameter sprocket (1), the teeth facing the chain guide surface (12) can be formed less likely to be affected by the directionality of the metal structure.

Further, the tooth width in the circumferential direction of the teeth facing the chain guiding surface (12) of the large diameter sprocket (1) is made wider than the tooth width in the circumferential direction of the teeth excluding the teeth facing the chain guiding surface. The reduction in strength of the teeth facing the guide surface (12) due to the provision of the chain guide surface can be reduced.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the multi-stage sprocket device of the present invention, FIG. 2 is a partially omitted bottom view, FIG. 3 is an explanatory view when changing chains, and FIG. 4 is a large-diameter sprocket only. A front view, FIG. 5 is a sectional view taken along line VV in FIG. 4, and FIG. 6 is FIG.
-VI line cross section, FIG. 7 is a perspective view of only the chain guide surface side portion of the large diameter sprocket, and FIG. 8 is an explanatory view showing another embodiment of the difficult meshing teeth. (1) …… Large sprocket (2) …… Small sprocket (11) …… First tooth (12) …… Chain guide surface

Claims (7)

[Scope of utility model registration request] 1. At least one large diameter sprocket (1).
Which has a large number of teeth circumferentially arranged at the chain pitch of the drive chain, and at least one small diameter sprocket (2) having the number of teeth of the large diameter sprocket (1) on the outer periphery. A multi-stage sprocket device comprising teeth having a smaller number of teeth and arranged at chain pitch intervals, said sprocket (1)
(2) on the tangential lead line drawn from the small interstitial center (O ₁ ) of the small diameter sprocket (2),
One interdental center (O ₂ ) on large sprocket (1)
So that they are positioned, and the center of each tooth (O ₁ )
The interval of (O ₂ ) is an integral multiple of the chain pitch, while the inner surface of the large sprocket (1) on the small sprocket side and the center of the tooth space (O ₁ ) (O ₂ ) The chain is separated from the small-diameter sprocket (2) at a position where the chain interferes with the large-diameter sprocket on the movement path when the chain moves, and the inter-tooth center (O ₂ ), The entire outer edge including the link plate of the chain intervenes when the teeth facing the rear side in the drive rotation direction start to intervene, and the size and the shape permitting the deviation toward the large diameter sprocket (1). A multi-stage sprocket device for a bicycle, which is provided with a chain guide surface (12) having and. 2. The chain guiding surface (12) is recessed from the interdental center (O ₁ ) side to the interdental center (O ₂ ) side edge, and the interdental center (O ₂ ) side. The inner sprocket-side inner link plate in the chain does not continue to run on the tooth that faces the rear side in the drive rotation direction with respect to the interdental center (O ₂ ) of the large-diameter sprocket (1). The multistage sprocket device for a bicycle according to claim 1, wherein the depth is set. 3. A first tooth (11) facing a rear side in a driving rotation direction with respect to a center (O ₂ ) between teeth of a large diameter sprocket (1).
The multi-stage sprocket device for a bicycle according to claim 1, wherein the teeth are easily meshing teeth that are easily meshed when the chain is changed from the small diameter sprocket (2) to the large diameter sprocket (1). 4. All the teeth except at least two teeth including the first tooth (11) facing the rear side in the drive rotation direction with respect to the center (O ₂ ) between the teeth of the large diameter sprocket (1) are replaced by small diameter sprockets ( The multi-stage sprocket device for a bicycle according to claim 1, wherein the teeth are hard to engage when the chain is engaged with the large diameter sprocket (1). 5. The multi-stage bicycle according to claim 1, wherein the chain guide surface (12) has different recess depths on the center (O ₁ ) side between the teeth and recess depths on the center (O ₂ ) side between the teeth. Sprocket device. 6. The interdental center (O ₂ ) side indentation depth of the chain guide surface (12) is made deeper stepwise than the interdental center (O ₁ ) side indentation depth. Multi-stage sprocket device for bicycles. 7. The large-diameter sprocket (1) according to claim 1, wherein the tooth width facing the chain guide surface (12) is wider than the tooth width except for the tooth facing the chain guide surface. Multi-stage sprocket device for bicycles.