JPH0140794Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention is used with a chain guide for a rear derailleur, more specifically, a multi-stage sprocket device attached to the rear wheel hub of a bicycle. This invention relates to a chain guide for a rear derailleur that changes gears by changing the chain.

(Prior Art) In general, this type of chain guide is composed of two pulleys, two pulley shafts that rotatably support these pulleys, and a plate that supports these pulley shafts. An annular recess having an outer circumferential surface and an inner circumferential surface is provided on the side surface of the pulley, and a cap having an annular lip extending into the annular recess is supported around the pulley shaft to prevent dust and dirt from entering the pulley bearing portion. This prevents muddy water from entering.

However, in the case of the structure in which the cap is provided, the effect of preventing the intrusion of dust and muddy water is small, so that dust and muddy water do not enter the bearing part of the pulley from the gap between the outer circumferential surface of the annular recess and the outer circumferential surface of the annular lip. There was a problem with the intrusion.

(Problems to be Solved by the Invention) The present invention attempts to solve the problem of the prior art in which dust and muddy water enter the bearing part of the pulley. By providing a seal body and an annular dam between the outer circumferential surface of the lip, it is possible to prevent dust and muddy water from entering the bearing portion of the pulley.

(Means for Solving the Problems) Accordingly, the present invention is a chain guide device equipped with two pulleys and a plate that rotatably supports these pulleys via a pulley shaft, and includes a An annular recess having an outer circumferential surface and an inner circumferential surface is provided, and a cap having an annular lip extending into the annular recess is supported around the axis of the pulley shaft. On one side of the circumferential surface of the annular lip,
An annular seal body having a seal portion is held, and the seal portion of the seal body is opposed to the other side circumferential surface, and the axis of the pulley is An annular weir rising in the radial direction was installed at the center side.

(Function) Dust and muddy water that try to enter the gap between the outer peripheral surface of the annular recess and the outer peripheral surface of the annular lip of the cap are prevented from entering by the sealing part of the seal body. Even if it were able to pass through the seal, the annular weir located inside would prevent further intrusion.

(Example) Hereinafter, an example of the chain guide according to the present invention will be described based on the drawings.

The illustrated chain guide includes two pulleys 1, 1 with shaft holes, two pulley shafts 2, 2 that rotatably support these pulleys 1, 1, and a plate 3 that supports these pulley shafts 2, 2. This chain guide and a link mechanism, that is, a link mechanism consisting of a base member A, two link members B, B, and a movable member C constitute a rear derailleur.

The chain guide according to this invention is provided with an annular recess having an outer circumferential surface 11a and an inner circumferential surface 11b on the side surface of the pulley 1 as shown in FIG. A cap 4 having a through hole 42 for receiving the pulley shaft 2 is supported so as not to rotate around the axis of the pulley shaft 2 while facing the side surface of the pulley 1, and the annular lip 41 is inserted into the annular recess 11. On the other hand, an annular seal body having an annular fitting portion 51 and an inward seal portion 52 protruding radially inward from the inner circumferential surface of the fitting portion 51 on the outer peripheral surface 11a of the annular recess 11. 5 is fitted and held, and the seal portion 52 of this seal body 5 is opposed to the outer peripheral surface of the annular lip 41 of the cap 4, and at the same time, from the outer peripheral surface of the annular lip 41 and from a position opposite to the seal portion 52. An annular weir 6 that rises radially outward is provided at the center of the pulley 1 in the axial direction.

In the above configuration, the seal portion 52 of the seal body 5 is placed in light contact with the outer peripheral surface of the annular lip 41 or in close proximity to the outer peripheral surface of the annular lip 41 to the extent that there is a slight gap, so that dust and muddy water can be removed from the seal portion 52. It makes it difficult for people to invade. Note that the seal portion 52
When the ring is brought into contact with the outer peripheral surface of the annular lip 41, the seal body 5, the pulley 1, and the cap 4 can be integrated into a unit, which has the advantage that the entire chain guide can be easily assembled.

Further, although an annular space S is provided between the seal portion 52 and the annular weir 6, this annular space S is not necessarily required. In this case, the seal portion 5
2 is brought close to the annular weir 6 so as to lightly touch it.

The annular weir 6 is formed by bending the tip of the annular lip 41, but it can also be formed by, for example, fitting a ring onto the outer peripheral surface of the tip of the annular lip 41 and using this ring as an annular weir. good. In addition to providing one annular weir 6 as shown in FIG. 1, a plurality of annular weirs 6 may be provided in parallel.

Furthermore, although the seal body 5 is made of rubber, it may also be made of other materials, such as synthetic resin.

Further, the cap 4 is formed of, for example, an aluminum plate, and the boss portion 1a of the pulley 1 is formed of a synthetic resin such as Juracon,
Further, the tooth portion 1b is formed of sintered metal.

Further, the cap 4 is clamped between the end surface of the bush 7 that fits on the pulley shaft 2 and the head 2a of the pulley shaft 2 or the plate 3, for example, by screwing the pulley shaft 2 onto the plate 3. Wear it.

Also, of the two pulleys 1, the guide pulley that guides the chain to the sprocket of the multi-stage sprocket device has an axial length that is a certain length shorter than the overall length of the pulley bush 2, as shown in FIG. Thus, the pulley 1 can be moved in the axial direction with respect to the pulley bush 2 by the tension of the chain.

It should be noted that this pulley 1 does not necessarily have to be movable in the axial direction relative to the pulley bush 2, but by doing so, after changing the chain using the overshift method, the pulley 1 will not be overloaded by the tension force of the chain. Since it returns by the stroke amount,
This will prevent noise after changing the chain.

In addition, 8 in the figure is a fitting bush that is fitted into the shaft hole of the pulley 1 so that it cannot rotate relative to the pulley 1.

Therefore, the outer peripheral surface 11 of the annular recess of the pulley 1
Dust or muddy water that attempts to enter the gap between the cap 4 and the outer peripheral surface of the annular lip 41 of the cap 4 is first prevented from entering by the seal portion 52.
Furthermore, even if it were to pass through the seal portion 52, the annular weir 6 located inside would prevent it from entering any further, and in the end it would not completely enter the bearing portion of the pulley 1. That's what happens.

In the embodiment described above, the seal body 5 is held on the outer peripheral surface 11a of the annular recess 11, and the annular weir 6 is provided on the outer peripheral surface of the annular lip 41 of the cap 4, but the opposite may be used.

In this case, as shown in FIG. 3, a seal body 5a having a seal portion 52a protruding radially outward from the outer peripheral surface of the annular fitting portion 51a is used, and
An annular weir 6a is provided that protrudes radially inward from the outer peripheral surface 11a of the annular recess 11.

Further, the annular recess 11 may be provided on both sides of the two pulleys 1, 1 as shown, or may be provided only on one side.

(Effects of the invention) As described above, the present invention holds an annular seal body having a seal portion on one side of the outer circumferential surface of the annular recess provided on the side surface of the pulley and the outer circumferential surface of the annular lip of the cap. Then, the seal portion of this seal body is opposed to the other side circumferential surface, and the seal portion rises radially on the other side circumferential surface and at a position closer to the axial center of the pulley than the opposing position of the seal portion. Since the annular weir is provided, even if dust or muddy water tries to enter the bearing part of the pulley through the gap between the outer circumferential surface of the annular recess and the outer circumferential surface of the annular lip, the seal section first prevents the intrusion. Moreover, even if it were able to pass through this seal, the annular weir located inside would prevent further intrusion. Therefore, as a whole, it is possible to prevent dust and muddy water from entering the bearing portion of the pulley, and it is possible to maintain smooth rotation of the pulley for a long period of time.

[Brief explanation of the drawing]

Fig. 1 is an enlarged sectional view of the main parts showing one embodiment of the chain guide of the present invention, Fig. 2 is an enlarged sectional view of only the main parts, and Fig. 3 is an enlarged sectional view of the main parts showing another embodiment. , FIG. 4 is a front view of the assembly assembled to the rear derailleur. 1... Pulley, 11... Annular recess, 11a...
...outer circumferential surface, 11b...inner circumferential surface, 2...pulley shaft, 41... annular lip, 4... cap, 5
... Seal body, 52 ... Seal portion, 6 ... Annular weir.

Claims (1)

[Scope of utility model registration request] A chain guide device comprising two pulleys and a plate that rotatably supports these pulleys via a pulley shaft, the chain guide having a plate on a side surface of the pulley,
An annular recess having an outer circumferential surface and an inner circumferential surface is provided, and a cap having an annular lip extending into the annular recess is supported around the axis of the pulley shaft. An annular seal body having a seal portion is held on one side circumferential surface of the annular lip, and the seal portion of this seal body is opposed to the other side circumferential surface, and A rear derailleur for a bicycle, characterized in that an annular weir rising in the radial direction is provided at a position closer to the axial center of the pulley than a position facing the seal portion.