JPS6111116Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is a bicycle sprocket assembly, more specifically, it consists of an annular body, a sprocket with a plurality of teeth provided around the outer periphery of the body, and a support tube that supports the sprocket. This invention relates to a bicycle sprocket assembly.

Conventionally, for this type of assembly, a plurality of protrusions are provided around the outer periphery of the support cylinder at predetermined intervals, and a fitting groove that fits with the protrusions is provided on the inner periphery of the body of the sprocket. One or more sprockets are fitted around the outer periphery of the support cylinder, and when using a plurality of sprockets, they are fitted sequentially from the largest diameter sprocket through spacers at regular intervals. Further, by fitting the fitting groove of each body into the protrusion, movement of the body in the circumferential direction with respect to the support tube is prevented, and pedal depression force is transmitted from the body to the support tube. is proposed.

However, when a fitting groove is provided on the inner periphery of the body of each sprocket as described above, there is no problem if the diameter of the body is large, but if the diameter of the sprocket is made small and the gear ratio is increased, the overall When the weight of the sprocket is reduced, the distance between the bottom of the tooth of the sprocket and the fitting groove located on the front side in the drive rotation direction of the body with respect to the tooth becomes shorter, and this short distance becomes The maximum drive torque acting on the sprocket will cause it to break.

Therefore, the diameter of the sprocket could not be made smaller than a predetermined value.

To solve the above problem, for example, in a multi-stage sprocket assembly in which a plurality of sprockets are combined, it is possible to reduce the diameter of the support cylinder relative to the smallest diameter sprocket of the support cylinder. The protrusions between the fitting grooves that fit into the teeth must have a strength that can withstand the maximum starting torque that acts on the meshing portion of the teeth with the drive chain, and the minimum spacing between the protrusions on the support cylinder, Since the minimum width of the protrusions and the minimum width of the groove between the protrusions are determined by themselves, the problem cannot be solved simply by reducing the diameter of the support tube. Since it is supported by the provided core via a one-way rotation mechanism, there is a limit to how small the diameter can be made, and it is not possible to fundamentally solve the above-mentioned problems.

The present invention was devised in view of the above-mentioned conventional problems, and while it is possible to reduce the minimum diameter of the sprocket, the space between the bottom of the sprocket tooth and the fitting groove can be destroyed by the maximum driving torque. Among the fitting grooves provided in the body, the reference fitting groove is set to a length that will not be destroyed by the maximum driving torque in the forward direction of the driving rotation direction of the body with respect to the bottom of the tooth. The remaining fitting grooves are provided around the reference fitting groove at a distance equal to the spacing between the protrusions, and the tooth bottom and the body A fitting groove having a spacing shorter than the minimum spacing between the fitting groove and the fitting groove located on the front side in the drive rotation direction, and the protrusion into which the fitting groove fits are omitted. be.

Embodiments of the present invention will be described below based on the drawings.

In the figure, 1... is a sprocket equipped with an annular body 11 and a plurality of teeth 12 provided around the outer periphery of the body 11, and 2 is a support cylinder that supports these sprockets 1... On the outer periphery of the cylinder 2, a plurality of protrusions 21 extending along the axial direction from one end edge are provided at predetermined intervals in the circumferential direction, and on the inner periphery of the body 11 of the sprocket 1... , a plurality of fitting grooves 13 that fit with the projections 21 are provided around the periphery.

The protrusions 21 and the protrusions 14 between the fitting grooves 13 that fit into the protrusions are formed to have a width that can withstand the maximum driving torque acting on the meshing portion of the teeth 12 with the drive chain.

Further, each of the sprockets 1... has a body 11 thereof.
The outer diameter of each sprocket 1 and the number of teeth 12 provided around the outer periphery of the body are different, and the inner periphery of each body 11 is sized to fit the outer periphery of the support cylinder 2. is inserted into the outer periphery of the support cylinder 2 and the fitting groove 13 is fitted into the protrusion 21, thereby preventing the body 11 from moving in the circumferential direction with respect to the support cylinder 2.

As described above, in this invention, among the fitting grooves 13 provided on the inner periphery of the body 11, one of the fitting grooves 13a serving as a reference is placed in front of the bottom 15 of the tooth 12 in the driving rotation direction of the body 11. side (Fig. 2 arrow x
direction side) with a minimum interval l that is longer than the length that will not be destroyed by the maximum driving torque acting on the meshing portion of the teeth 12 with the drive chain, and the remaining fitting grooves 13 excluding the reference fitting groove 13a. are provided around the reference fitting groove 13a at an interval equal to the interval p between the protrusions 21. 15, a short width fitting groove 13b with a fitting groove 13 located on the front side in the driving rotation direction of the body 11, and a short width fitting groove 13b having a spacing shorter than the minimum spacing l, and the protrusion 2.
1..., by omitting the protrusion 21a into which the short width fitting groove 13b fits, the tooth bottom 15 and all the fitting grooves located on the front side in the driving rotation direction of the body 11 with respect to the tooth bottom. 13 is the minimum distance l.
This is the interval above.

A screw 22 is provided on the inner periphery of one end of the support cylinder 2, and a collar 23 that projects radially outward is provided on the outer periphery of the other end. Also, the illustrated support tube 2
constitutes a driving member of a multi-stage freewheel, and has a ratchet 24 on its inner periphery that engages with a pawl of a driven member of the freewheel, a ball race 25 provided outside the ratchet 24 in the axial direction, It has 26.

The assembly of the present invention is constructed as described above, and each of the sprockets 1 is fitted onto the outer periphery of the support tube 2 from the largest diameter sprocket through the spacer 3 at regular intervals. The fitting groove 13 is fitted into the protrusion 21 to prevent each body 11 from moving in the circumferential direction, and the end surface of the largest diameter sprocket is brought into contact with the collar 23 to tighten the screw 2.
By screwing an annular stopper 4 into the support cylinder 2, the respective bodies 11 are prevented from moving in the axial direction, and each body 11 is immovably attached to the support tube 2. The support tube 2 supporting the sprocket 1 is rotatably supported by a driven member of the freewheel via a large number of balls, and the force applied to the pedal is transferred to the sprocket via a drive chain suspended on the sprocket 1. The power is transmitted from the body 11 of 1 to the driven member via the support tube 2 and the pawl that engages with the ratchet 24, thereby driving the rear hub. However, a protrusion 21 is attached to the support tube 2.
Also, when providing a fitting groove 13 in the sprocket 1, the height of the protrusion 21 and the depth of the fitting groove 13 are set so that there is a gap between one protrusion 21 and one fitting groove 13. In addition to ensuring that a predetermined fitting strength is obtained, the minimum distance 1 between the reference fitting groove 13a and the tooth bottom 15 is set.

Since the number of the protrusions 21 and the fitting grooves 13 is determined taking into consideration the strength of the fit between the protrusions 21 and the fitting grooves 13 and taking into account the safety range, for example, as shown in FIG. When 12 fitting grooves 13 are provided, two protrusions 21a and fitting grooves 13 are provided.
Even if b is omitted, the strength of the fit between the sprocket 1 and the support tube 2 is not significantly affected.

Furthermore, in the case of a multistage sprocket assembly in which a plurality of sprockets 1 are combined as shown in FIG.
It is provided to correspond to the driving torque that acts on the large diameter sprocket.

This driving torque changes depending on the load, and the driving torque acting on the small diameter sprocket on the top side is smaller than that on the large diameter sprocket on the low side.

Therefore, the number of protrusions 21 in the part that supports the small diameter sprocket is large compared to the required transmission torque, so for example, as shown in FIG.
In the case of a small-diameter sprocket having 12 sprockets, even if two fitting grooves 13 and two protrusions 21 are missing, the strength of the fit between the small-diameter sprocket 1 and the support tube 2 is not affected.

In the above construction, the outer periphery of the support tube 2 is formed straight to support the sprocket 1.
Alternatively, the outer periphery of one end of the support cylinder 2 may have a large diameter, and the outer periphery of the other end may have a small diameter, so that the large diameter part supports a large diameter sprocket, and the small diameter part supports a small diameter sprocket.

Further, although a plurality of sprockets 1 are used, it may be one sprocket.

As described above, the present invention provides that, among the fitting grooves provided in the body of the sprocket, the standard fitting groove has a minimum length that is greater than or equal to the length that will not be destroyed by the maximum driving torque in the forward direction of the driving rotation direction of the body with respect to the tooth bottom. The remaining fitting grooves are provided at intervals equal to the intervals of the protrusions provided on the outer periphery of the support cylinder with respect to the reference fitting groove, while The sprocket is formed to have a small diameter because the fitting groove, which has an interval shorter than the minimum interval with the fitting groove located on the front side in the drive rotation direction, and the projection into which the fitting groove fits are omitted. The gear ratio can be increased and the whole body can be made lightweight, and the distance between the tooth bottom and all the fitting grooves located on the front side in the driving rotation direction of the body with respect to the tooth bottom can be set to be at least the minimum distance. Because it can be spaced,
Damage to the body due to the maximum driving torque can be reliably prevented.

Further, by omitting a part of the fitting groove provided in the body and the protrusion provided on the outer periphery of the support cylinder, the direction in which the body is fitted into the support cylinder is determined, so that incorrect fitting of the body can be reliably prevented. This makes it possible to always maintain the spacing above the minimum spacing.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing an embodiment of the assembly of the present invention, and FIG. 2 is a sectional view taken along the line of FIG. 1. 1...Sprocket, 11...Body, 12...
...teeth, 13...fitting groove, 13a...standard fitting groove,
15...Tooth bottom, 2...Support cylinder, 21...Protrusion.

Claims (1)

[Scope of utility model registration request] It consists of an annular body, a sprocket with a plurality of teeth provided around the outer periphery of the body, and a support cylinder that supports the sprocket, and a plurality of protrusions are arranged at predetermined intervals on the outer periphery of the support cylinder. The body is provided with a fitting groove that fits into the protrusion, and the fitting of the fitting groove into the protrusion prevents the body from moving in the circumferential direction with respect to the support cylinder. The bicycle sprocket assembly is provided with a length that does not destroy the reference fitting groove among the fitting grooves provided in the body with maximum driving torque in the forward direction of the driving rotation direction of the body with respect to the tooth bottom. At the same time, the remaining fitting grooves are provided around the reference fitting groove at an interval equal to the interval between the protrusions, and the tooth bottom and the body A bicycle, characterized in that a fitting groove having an interval shorter than the minimum interval with the fitting groove located on the front side in the drive rotation direction and the protrusion into which the fitting groove fits are omitted. Sprocket assembly.