JPH0537759Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

This invention relates to a bicycle freewheel.
Specifically, the present invention relates to an improved bearing structure and one-way clutch mechanism constructed between a core and a sprocket support cylinder so that dust, dirt, water, etc. are less likely to enter from the outside.

[Conventional technology]

A bicycle freewheel consists of a sprocket support tube that is rotatably supported relative to a core fixed to the hub of the rear wheel via multiple steel balls, and a sprocket support tube between the core and the sprocket support tube. The sprocket includes a one-way clutch mechanism, and one or more sprockets provided on the outer periphery of the sprocket support cylinder.
As a result, the force exerted by the chain on the sprocket to rotate the sprocket support cylinder in the forward direction is transmitted directly to the core or hub, and the driving force from the pedals is transmitted to the wheels, while the sprocket support cylinder It can freely rotate in the opposite direction relative to the core or hub.

[Problem that the invention attempts to solve]

By the way, since the sprocket support tube can rotate relative to the core as described above, there is a gap between the inner circumference of the sprocket support tube and the outer circumference of the core, and from this gap there is a gap between the inner circumference of the sprocket support tube and the outer circumference of the core. There is a problem in that dust, dirt, or water gets into the internal space formed between the sprocket support cylinder and the core. In particular, between the core and the sprocket support tube, there is a bearing mechanism consisting of a large number of steel balls that roll while being sandwiched between ball bearing surfaces formed on both sides, and a bearing mechanism that is made up of a large number of steel balls that roll while being sandwiched between ball bearing surfaces formed on both sides, and a Since the one-way clutch mechanism is composed of the formed ratchet tooth row and the ratchet pawl that is supported on the outer periphery of the core so that it can be undulated and swung, dust can enter the internal space from the gap between the core and the sprocket support cylinder. If water or the like gets into the bearing mechanism, this will severely impede the rotational performance of the bearing mechanism or prevent the one-way clutch mechanism from operating properly. This idea was devised under the above circumstances, and was designed to make it difficult for external dust, water, etc. to enter through the gap between the core and the sprocket support tube.
Moreover, it is an object of the present invention to provide a bicycle freewheel that does not deteriorate the workability of assembling the freewheel itself or the rotational performance of the sprocket support tube.

[Means to solve the problem]

In order to solve the above problems, the present invention takes the following technical measures. That is, the present invention provides a bicycle freewheel comprising a core fixed to a hub and a sprocket support tube rotatably supported with respect to the core. , a cylindrical base fitted on the outer periphery and extending axially inward, a flange-shaped vertical wall extending radially outward of the freewheel from the outer end of the cylindrical base, and an outer periphery of the vertical wall. A dust-proofing member having a cylindrical part bent inward in the axial direction of the freewheel is installed at the axial end of the sprocket support cylinder, and the inner and outer surfaces of the cylindrical part of the dust-proofing member, the vertical wall part or the above-mentioned By integrally forming a dust-proof wall that faces the cylindrical base in a non-contact manner with a gap in between, it is possible to prevent air flow from outside the freewheel along the dust-proof member in cross section between the sprocket support cylinder and the core. The present invention is characterized in that a gap is formed that extends in a zigzag shape toward the inside of the freewheel in the radial direction without forming a portion that goes outward in the radial direction of the freewheel and communicates with the inside of the freewheel. .

[Effect]

By taking the above measures, the gap formed between the sprocket support cylinder and the core, in its cross section, first extends from the inlet to the back in the axial direction of the freewheel, and then extends radially inward. Bend, then bend outward in the axial direction,
It then bends radially inward, eventually leading to an interior space in which the bearing structure and one-way clutch mechanism are incorporated. In other words, the above-mentioned gap bends in a zigzag shape in its cross section, radially inward of the freewheel without forming a radially outward portion, and finally forms the inner space. reach. In this way, the gap between the core and the sprocket support cylinder is not directly connected to the bearing structure in the internal space as in the conventional case, but is bent in a zigzag shape, so this zigzag-shaped gap By being blocked by the wall, the probability that dust, etc. that have entered the entrance of the gap will reach the internal space is extremely low. Moreover, since the clearance extends radially inward of the freewheel, the probability that the dust will reach the internal space during rotation of the sprocket support tube is further reduced. That is, while the sprocket support tube is rotating, centrifugal force acts on the dust that has entered the gap, so it is almost impossible for the dust to go radially inward through the gap against this centrifugal force. Moreover, since the dust-proof member and the dust-proof wall face each other in a non-contact state, no frictional force acts between the core and the sprocket support tube, unlike when a dust seal is provided. The rotational efficiency of the sprocket support tube does not decrease.

【effect】

As described above, in the bicycle freewheel of the present invention, the gap formed by the dustproof member provided on the core or screw cap and the dustproof wall provided on the sprocket support tube is narrowed from the outside of the freewheel to the inside in the radial direction. Since it is constructed so that it extends toward the inside of the freewheel, even if mud or water gets into between the core and the sprocket support tube from the outside while the bicycle is running, the above-mentioned gap will be filled in this way. The mud and water that have entered the sprocket are forced back through the gap by the centrifugal force caused by the rotation of the sprocket support cylinder and are discharged to the outside. Therefore, according to the present invention, it is possible to reliably prevent mud and water that have entered the gap between the core and the sprocket support tube from entering the freewheel internal space. Therefore, even if the vehicle is repeatedly driven on rough roads in rainy weather, the rotational performance of the freewheel bearing portion will not deteriorate. Moreover, the dustproof member and the dustproof wall are not in contact with each other,
Moreover, since they are axially opposed, the rotation of the sprocket support cylinder is maintained in an extremely smooth state, and the ease of disassembly and assembly is maintained.Furthermore, even after disassembly and assembly, the dustproof member and the dustproof It also has the effect of reliably reproducing a non-contact state with the wall.

[Explanation of Examples]

Hereinafter, embodiments of the bicycle freewheel of the present invention will be specifically described with reference to the drawings. The drawings show an example in which the present invention is applied to a so-called multi-stage freewheel in which a plurality of sprockets of different diameters are attached to a sprocket support cylinder. First, the basic structure of the freewheel will be explained. The core 10 to be screwed into the male threaded part of the hub (not shown) has an inner large diameter part 11 and an intermediate thick part 1.
2 and an outer small diameter portion 13. Inner large diameter part 1
On the outer periphery of the part slightly deeper from the inner end of 1,
The first ball receiving surface 14 is located on the outer periphery of the outer small diameter portion 13.
Male screw 1 for screwing the screw cap 15 to be described later
6 are formed respectively, and a ratchet pawl 17 is semi-embedded in the outer periphery of the intermediate thick portion 12 so as to be able to rise and fall while being biased in the upright direction. On the other hand, the sprocket support cylinder 20 has a cylindrical shape that can be fitted onto the outer periphery of the core 10 from the right side in FIG. A ratchet tooth row 22 is formed on the inner periphery of the intermediate portion of the third ball receiving surface 21 facing the ratchet pawl 17, and a fourth ball receiving surface 23 is formed on the inner periphery of the outer portion. On the outer periphery of this sprocket support cylinder 20, a plurality of sprockets 24a, 24b, .
a, 25b, . . . at predetermined intervals so as to be non-rotatable relative to the sprocket support cylinder 20. In the illustrated example, after spline-fitting the four large-diameter sprockets among the five sprockets, the smallest-diameter sprocket 24e is attached to the support cylinder 2.
It is screwed onto a male thread 20a formed on the outer periphery of the outer part of 0. A sprocket support cylinder 20 is attached to the core 10.
A plurality of steel balls 26 are inserted between the first ball receiving surface 14 and the third ball receiving surface 21 so that they can roll, and are fitted from the right side in FIG. The screw cap 15 on which a second ball receiving surface 18 is formed allows a plurality of steel balls 27 to roll between the second ball receiving surface 18 and the fourth ball receiving surface 23 of the sprocket support cylinder 20. Assembling the freewheel is completed by screwing it onto the male thread 16 while interposing it. In addition, in FIG. 2, the reference numeral 28 indicates the core 20.
The outer end wall 12a of the middle thick wall portion 12 and the screw cap 1
An adjustment washer is shown which is appropriately interposed between the sprocket support cylinder 20 and the inner wall 15a of the sprocket support cylinder 20 to adjust the rotational tone of the sprocket support cylinder 20. With the above configuration, the sprocket support cylinder 20
The first bearing part B1 is formed by the first and third ball bearing surfaces 14, 21 and the steel balls 26 interposed between these, and the second and fourth ball bearing surfaces 18, 23. and a second bearing part B2 formed by a steel ball 27 interposed therebetween, it is rotatably supported with low friction with respect to the core 10, and is connected to the ratchet pawl 17 and the ratchet tooth row. The ratchet mechanism R consisting of 22 makes it possible to transmit only the rotational force in the driving direction to the core 10. Now, in this invention, the dustproof structure D
is added. That is, the core 10 or/and this core 1
On the outer periphery of the end of the screw cap 15 that is integrally assembled to the outer end of the freewheel, there is a standing wall portion 29a extending outward in the radial direction of the freewheel, and a wall portion 29a extending inward in the axial direction of the freewheel from the outer periphery of the standing wall portion 29a. The dustproof member 29, which has a cylindrical portion 29b that is bent, is attached at its base 29c, while the dustproof member 29 is attached to the end of the sprocket support cylinder 20 through a certain gap 31 inside the dustproof member 29 in a non-contact manner. Dust-proof walls 30 facing each other in the axial direction are integrally formed. The dustproof member 29 is made by press-molding a plate material of a predetermined thickness, and the cylindrical base 29c is connected to the core 1.
0 and the screw cap 15 by fitting into the outer circumferential surfaces of the ends thereof. Then, the dustproof member 29
Specifically, the dustproof wall 30 that is to be integrally formed so as to face each other with a certain gap 31 on the inside of the dustproof member 29 is
an annular recessed groove 30a recessed in the axial direction on the end face of the sprocket support 20 so as to surround the sprocket in a U-shape;
The dustproof member 29 has a substantially U-shaped cross section, and is combined with a flange portion 30b that protrudes outward in the axial direction so as to protrude into the inner concave side of the dustproof member 29. As a result of the above, the dustproof wall 3 formed on the outer periphery of the cylindrical portion 29b of the dustproof member 29 attached to the core 10 and the screw cap 15 and the sprocket support cylinder 20
In the cross section, the gap 31 formed between the groove 30a and the inner surface of the groove 30a extends axially from the entrance, bends inward in the radial direction, then bends outward in the axial direction, and then extends in the radial direction. After bending inward and further axially axially, the bearing part B is bent in a zigzag manner without forming a part that faces radially inward and radially outward.
1, it will reach B2. For this reason, the gap 3
Dust etc. that have entered the inlet of bearing part B1,
In order to penetrate to B2, it has to hit the wall of the gap and bend many times, so the probability that dust etc. will pass through the gap 31 and reach the bearing parts B1 and B2 is extremely small. Further, since this gap 31 communicates with the internal space while heading substantially radially inward, the above probability becomes even smaller. That is, since centrifugal force acts on the dust while the sprocket support tube 20 is rotating, it is unlikely that the dust will invade inward in the radial direction against the centrifugal force. Note that it goes without saying that it is better for this gap 31 to be as small as possible. Of course, the scope of the present invention is not limited to the embodiments described above; for example, the embodiments described above are examples in which the present invention is applied to a so-called multi-stage freewheel in which a sprocket support cylinder supports a plurality of sprockets of different diameters. However, it goes without saying that the present invention can be similarly applied to a so-called single freewheel constructed by integrally forming a single sprocket on a sprocket support cylinder. In addition, the illustrated example shows the gap between the sprocket support cylinder and the core at the hub side end of the freewheel;
Although the present invention is applied to both the gap between the sprocket support tube and the screw cap at the outer end of the freewheel, it is of course possible to apply the present invention to only one of them.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway sectional view of an embodiment of the bicycle freewheel of the present invention, and FIG. 2 is an enlarged sectional view of the main part of the example shown in FIG. 10... core, 20... sprocket support cylinder,
29...dustproof member, 29a...standing wall part, 29a
...Cylindrical part, 30...Dust-proof wall.

Claims (1)

[Claims for Utility Model Registration] In a bicycle freewheel comprising a core fixed to a hub and a sprocket support tube rotatably supported with respect to the core, the axial end of the core or screw cap a cylindrical base fitted to the outer periphery of the part and extending axially inward; a flange-shaped upright wall extending radially outward of the freewheel from the outer end of the cylindrical base; and the upright wall. A dustproof member is attached to the axial end of the sprocket support tube, and the inner and outer surfaces of the cylindrical part of the dustproof member and the vertical wall part are attached to the axial end of the sprocket support cylinder. Alternatively, by integrally forming a dust-proof wall that faces the cylindrical base in a non-contact manner with a gap therebetween, the dust-proof member It is characterized by forming a gap that extends in a zigzag shape toward the inside of the freewheel in the radial direction of the freewheel without forming a portion that goes radially outward of the freewheel along the freewheel, and communicates with the inside of the freewheel. A freewheel for bicycles.