JPH0717669Y2 - Bicycle gearbox - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field and Outline of the Invention] The present invention relates to a bicycle transmission, and is designed to enable smooth gear shifting.

[Prior Art and its Problems] A bicycle equipped with a transmission has a multi-stage chain gear device, which is configured by combining a large number of large and small chain gears, with a rear wheel hub and a crank. In, a chain is hung on a pair of chain gears. The chain is displaceable in the left-right direction by a chain guide of a derailleur working in conjunction with a shift lever, and can be engaged with another chain gear by the moving force in the left-right direction.

By the way, in the conventional transmission, when changing the chain from the small diameter chain gear to the large diameter chain gear, even if the chain is displaced to the large diameter chain gear side by the derailleur, the outer surface of the link plate of the chain has a large diameter. It interferes with the inner surface of the tooth portion of the chain gear and is received by the large-diameter chain gear. As a result, the chain is overshifted to the outer side of the tooth portion of the large-diameter chain gear, and the side surface of the large-diameter chain gear. The chain will not be picked up by the teeth of the large diameter chain gear unless it is pressed firmly against. Also, when changing the chain from the large diameter chain gear to the small diameter chain gear, the inner surface of the chain link plate is strongly pressed against the outer surface of the tooth portion of the large diameter chain gear, and due to the pressing force, The large chain gear of the chain is not easily disengaged from the teeth. Therefore, the conventional transmission cannot switch gears smoothly.

[Problem] The present invention moves the chain (C) left and right by such a "chain guide (20), and the chain (C) is hung between the large and small chain gears as the chain (C) travels. It is an object of the present invention to make it possible to smoothly shift gears in a "bicycle gear shift device".

<< Regarding the Invention of Claim 1 >> [Technical Means] The technical means of the present invention taken to solve the above problems are as follows.
[For large-diameter chain gears, a slit (S) that inclines inward from the root toward the front in the forward rotation direction is cut open, and the wall surface behind the slit (S) inclines outward toward the rear. And the open area of the slit (S) is set to a range including at least one tooth on the front side with respect to the open end of the slit (S). "

[Operation] The above technical means operates as follows.

When the chain guide (20) is moved from the small diameter chain gear side to the large diameter chain gear side, the chain (C) located in the portion of the chain guide (20) resists this tension and the outer peripheral side of the large diameter chain gear. Located in. The chain (C) is inclined between the small diameter chain gear and the chain guide (20). In this case, since the side wall surface on the rear side of the slit (S) is inclined outward toward the rear, when the large diameter chain gear rotates and the chain (C) reaches the position of the slit (S). , The link plate on the outside of the chain (C) enters the slit (S). Then, the invading link plate is hooked with the slit (S), and the chain (C) is pulled up to the tooth tip side to engage with the tooth.

At this time, the chain (C) runs in the chord direction of the large-diameter chain gear between the small-diameter chain gear and the chain guide (20), but the cutting direction of this slit (S) is inclined forward. Therefore, the running portion of the chain (C) can engage with the inclined slit (S) in a wide range, and the teeth of the chain (C) and the teeth can be easily engaged with each other.

Further, the open-cut area of the slit (S) is set to a range including at least one tooth on the front side with respect to the open end of the slit (S), and moreover, the slit (S) is inclined toward the inner peripheral side from the tooth bottom toward the front in the forward rotation direction. Therefore, the outer peripheral side portion of the slit (S) functions as a bending portion, and the chain (C) easily transfers to the teeth of the large diameter chain gear.

On the contrary, when the chain guide (20) is moved from the large diameter chain gear to the small diameter chain gear, the chain guide (20) is switched to the small diameter chain gear side in the same manner as the conventional one. Also in this case, when the chain guide (20) is moved to the small-diameter chain gear side, the outer peripheral side portion of the slit open-cut area functions as a bending portion, and the tip of the chain travels as the chain travels. Displaces to the gear side. Therefore, the running direction of the chain (C) and the direction in which the teeth of the large-diameter chain gear are aligned are deviated from each other, and the chain (C) is easily and easily disengaged from the large-diameter chain gear to engage with the small-diameter chain gear. .

[Effects] The present invention having the above-described configuration has the following unique effects.

When the chain (C) is switched from the small-diameter chain gear to the large-diameter chain gear, the chain (C) is pulled up to the addendum with the link plate caught in the slit (S). Compared with the chain, the chain (C) can change gears reliably and without slipping.

In particular, since the cutting direction of the slit (S) coincides with the running direction of the chain when the chain is transferred to the large diameter chain gear, the link plate and the slit (S)
The rear wall surface is easy to get caught. Also, slit (S)
Since the outer peripheral portion of the chain can bend to the left and right, there is little operation resistance when changing the chain (C) when changing the chain between the large and small chain gears. In this respect, the gear shift can be performed more smoothly and reliably as compared with the above-described structure having no slit (S).

<< Regarding the Invention of the Second Claim >> The invention of the second claim specifies the wall surface shape of the slit (S) in the invention of the first claim, and the specified technical means is "slit (S)". The front side wall surface is formed substantially parallel to the rear side surface. ”

When the chain guide (20) is moved to the large-diameter chain gear side, the running posture of the chain (C) and the constituent wall of the slit (S) at the occlusal portion match in plan view, and the outside of the chain (C) The link plate easily enters the slit (S), and the chain (C) easily catches on the slit (S). Therefore, the shift change can be performed more smoothly.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

In the transmission of this embodiment, as shown in FIGS. 1 and 2, the front side multi-stage chain gear (FG) is composed of a large diameter chain gear (3) and a small diameter chain gear (4).
The rear side multi-stage chain gear (RG) is composed of five chain gears having different numbers of teeth, and the chain (C) is hung between them.

A front derailleur (F) is attached to the front side multistage chain gear (FG), and a rear side multistage chain gear (RG).
The rear derailleur (R) is installed corresponding to each of them, and it is possible to perform 10-speed shifting by combining each multi-stage chain gear.

The front derailleur (F) is equipped with a chain guide (20) that moves in the axial direction of the front side multistage chain gear (RG), and by moving this chain guide (20) in the axial direction (movement in the left-right direction). , Chain (C)
Is engaged with one of the large-diameter / small-diameter chain gears (3), (4), and the rear derailleur (R) has a pair of pulleys (P), (P). A frame (Y) is provided, and the chain (C) is hooked on one of the chain gears by moving the hooking frame (Y) in the axial direction of the rear-side multistage chain gear. .

The chain gear of the present invention applied to the transmission configured as described above will be described.

In this embodiment, the present invention is applied to the large diameter chain gear (3) of the front side multi-stage chain gear (FG). As shown in FIGS. 3 and 5, the large diameter chain gear (3) is used. A slit (S) inclined forward by 45 ° from the root toward the inner circumference is cut in a portion located rearward of the left crank arm, and the side wall surface on the rear side of the slit (S) is opened. , The inclined surface (38) facing outward.

In this embodiment, the slit (S) has an opening length of 25 mm and an opening width of 1.5 mm.
Further, the inclination range of the inclined surface (38) is set from the slit (S) to the tooth root one rearward.

Therefore, in this bicycle transmission, the chain guide (20) of the front derailleur (F) is moved outward by the operation of the shift lever attached to the vehicle body, the steering wheel, or the like, and the small diameter chain gear (4) is accordingly moved. The chain (C) hung on () pushes the large-diameter chain gear (3) outward, but when the chain (C) rotates and reaches the position of the slit (S) described above, the chain (C) shown in FIG. As shown in FIG. 4, the chain link penetrates into the vicinity of the bottom of the slit (S), and the chain (C) is pushed up to the tooth tip of the large diameter chain gear (3) along the slit (S) upward. .

Therefore, the long inclined surface along the flow of the chain (C) from the vicinity of the bottom of the slit (S) to the rear tooth tip catches the chain (C) and picks it up. ) Is guided to the addendum of the large-diameter chain gear (3) without slipping and without difficulty, and stays in the proper position.

The chain (C) is changed by operating the shift lever when the left crank arm is located slightly forward of the uppermost portion in the rotational direction and further depresses further.

Further, in the above-mentioned embodiment, the slit (S) is cut in the forward direction toward the inner circumference, but the slit (S) is cut in the radial direction from the tooth bottom and is continuous with this. It is also possible to use an L-shaped member that is formed by cutting open toward the front.

The one shown in Fig. 6 has a radial cutting distance of 10 mm,
The cutting distance toward the front is set to 30 mm, and the large-diameter chain gear (3) is formed with a bending portion (T) of a length having three teeth at the peripheral portion, and the radius at the slit (S) The side wall surface on the rear side of the direction cutting portion is inclined outward toward the rear.

In this case, in addition to the effects of the above-described embodiment,
When moving the chain guide (20) to the left,
As shown in FIG. 7, the tip of the bending portion (T) is displaced toward the small-diameter chain gear side, and the running direction of the chain (C) and the direction in which the teeth of the large-diameter chain gear are aligned are displaced. The chain (C) is easily disengaged from the large-diameter chain gear and smoothly meshes with the small-diameter chain gear.

Further, in the above-mentioned two embodiments, only the side wall surface on the rear side of the slit (S) is inclined, but this is as described in the technical means of the invention of the second claim. The front side wall surface may be inclined in parallel with the rear side inclined surface. In this case, due to the described operation, the shift change becomes smoother.

In all of the above-mentioned embodiments, the front side multi-stage chain gear (FG) has two stages, but the present invention may be adopted for three or more stages, in which case the innermost minimum The present invention may be applied to other than the chain gear. In addition, the rear multi-stage chain gear (F
The present invention may be adopted in G).

The present invention can also be applied to the case of an elliptical deformed gear.

[Brief description of drawings]

1 and 2 are explanatory views of a bicycle transmission, and FIGS. 3 to 7 are explanatory views of an embodiment in which the present invention is applied to a large-diameter chain gear, and in FIG. …… Chain (S) …… Slit (20) …… Chain guide

Claims (2)

[Scope of utility model registration request] 1. A bicycle for which a chain (C) is moved left and right by a chain guide (20) so that the chain (C) can be switched between large and small chain gears as the chain (C) travels. In a transmission, in a large-diameter chain gear, a slit (S) that inclines toward the inner peripheral side from the tooth bottom toward the front in the forward rotation direction is opened and cut, and the wall surface on the rear side of the slit (S) is moved backward. For a bicycle, which has an inclined surface (38) which is inclined outwardly toward the outside and which has an opening and cutting area of the slit (S) set to a range including at least one tooth on the front side with respect to the open end of the slit (S). Gearbox. 2. The bicycle transmission according to claim 1, wherein the front wall surface of the slit (S) is formed substantially parallel to the rear wall surface of the utility model.