JPS6034826Y2 - bicycle freewheel - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention relates to bicycle freewheels, and more specifically, the diameter of the sprocket can be made small, and the sprocket teeth can be formed by punching press. This invention relates to a device that has been improved to ensure a high load bearing capacity, durability, and rotational performance.

[Conventional technology]

Recently, mini cycles and other bicycles for women and children have become rapidly popular, and due to the demand for lighter weight mini cycles, the chain wheel (front gear) and freewheel (rear gear) have been made with smaller diameters. There is a tendency towards change.

Furthermore, since mini-cycles have small diameter wheels, in order to extend the mileage per petal crank rotation, it is necessary to further reduce the outer diameter of the freewheel and reduce its number of teeth.

However, since the screw diameter of the hub to which the freewheel core is screwed is set to a certain size by Japanese Industrial Standards, it has traditionally been easy to reduce the number of freewheel teeth while maintaining a certain level of strength and performance. It wasn't.

Examples of freewheels configured to reduce the number of teeth include Utility Model Publication No. 56-7713.
There is something described in the No.

As shown in FIG. 4 of the present application, a part of the cylindrical body C of the free gear body having sprocket teeth a on the outer periphery is bulged out in a substantially inverted ■ shape, and an upper ball is formed on the inner surface of the free gear body. While forming the race surface d, the ratchet pawl support part f of the core e
A lower ball race surface having a cross-section of a square shape, which tapers inwardly in the radial direction by forming the opposing surfaces of the screw cap g screwed onto the one end and the extension of the ratchet pawl support. By forming a steel ball group 11 between these ball race surfaces d and h, the free gear body is configured to be freely rotatably supported relative to the core e.

That is, in this conventional freewheel, the free gear body is supported against the core e by a single ball bearing part, and the inverted V-shaped ball race surface d is connected to a part of the barrel part e. It is formed by bulging outward, so that the outer diameter of the free gear body on which the sprocket tooth portion a is to be provided can be relatively reduced compared to a conventional example.

[Problem that the invention attempts to solve]

However, in such a ball bearing structure,
Since the single ball race must support the reaction force caused by the rotation of the pedal, it is not strong enough, and the steel ball rolls into contact with the upper and lower ball race surfaces at 4 points, 2 points each on the top and bottom. Therefore, there is a problem in that adjustment to equalize the contact pressure at these four points is extremely troublesome.

In order to solve such problems, for example,
It is conceivable to form a ball bearing part on the left side of the tooth part similar to that formed on the right side of the tooth part in FIG. 4, as shown in Publication No. 7-11007, but this method cannot be adopted in practice.

That is, if the teeth of a bicycle freewheel were cut one by one using a gear cutting machine, the cost would increase significantly.

By providing bulges on both the left and right sides of the teeth as described above,
Because the die of the punching press cannot be applied to the teeth,
This means that teeth cannot actually be formed.

As shown in Fig. 4, in the case where only the cylinder body on one side of the tooth section is to be bulged out, all the teeth are simultaneously It can be formed by punching and press forming.

Furthermore, in the conventional freewheel structure as shown in Fig. 7 of Japanese Utility Model Publication No. 56-9856, the structure of the freewheel, which has been generally adopted in the past, has a screw cap that is screwed to the core, and a cylindrical body of the free gear body. Since the sprocket requires a certain level of strength, it has not been possible to unnecessarily reduce the diameter of the screw cap or to reduce the outer diameter of the sprocket by thinning the cylindrical body of the free gear body.

This invention was devised under the above circumstances, and it solves the problems of each of the conventional examples mentioned above, and basically replaces the conventional two-row ball lace. By adopting a bearing structure of The objective is to provide a bicycle freewheel with a new structure that allows for

[Means to solve the problem]

In order to solve the above problems, the present invention takes the following technical measures.

That is, a free gear body is provided with sprocket teeth on the outer periphery of the axially intermediate part, a first ball bearing has a surface on the inner periphery of the axially inner part, and a second ball bearing has a surface on the inner periphery of the axially outer part. The third ball receiver has a surface on the outer periphery of the outer part, and the fourth ball receiver has a surface on the outer periphery of the screw lid screwed on the outer part in the axial direction. The third ball receiver above is between the faces,
and a bicycle freewheel rotatably supported by a group of steel balls being removably interposed between a surface of the second ball holder and a surface of the fourth ball holder; The second ball bearing is located on the outside in the radial direction of the surface, with the radius of the outer periphery of the inner cylinder body inward from the sprocket teeth and the outer periphery of a portion of a predetermined length adjacent to the outside of the sprocket teeth. The first ball bearing has a surface radius smaller than the radius of the outer periphery of the outer cylinder body by a dimension approximately corresponding to the height from the base of the sprocket tooth to the bottom of the sprocket tooth. The ball receiver is made smaller in size than the radius of the surface by the difference in radius between the outer circumference of the inner cylinder body and the outer circumference of the outer cylinder body, so that the thickness of the inner cylinder body is equal to the thickness of the outer cylinder body. The thickness of the third ball bearing is the same, and the surface of the third ball bearing is hollowed out radially inward from the outer circumferential surface of the core to have a substantially semicircular cross section, and the steel ball contact portion at the bottom thereof is The radius of the fourth ball bearing is made smaller than the radius of the steel ball abutting portion of the surface of the fourth ball bearing by the difference in radius between the surface of the first ball bearing and the surface of the second ball bearing.

[Action and effect]

In bicycle sprockets, the diameter of the tooth bottom is larger than the outer diameter of the cylindrical part of the gear body so that the lower edge of the link plate does not come into contact when the chain roller fits into the tooth bottom. .

That is, the tooth bottom is located at a position higher than the outer diameter of the gear body to some extent.

In the present invention, the radius of the outer periphery of the part where the sprocket teeth of the free gear body are provided or the inner part thereof is reduced by approximately the height of the tooth bottom than the radius of the outer periphery of the outer cylinder body.

As a result, the sprocket diameter of the freewheel of the present invention can be made smaller than the conventional one by an amount equivalent to twice the tooth bottom height.

In addition, in the present invention, only the outer cylinder body of the sprocket teeth bulges out to correspond to the diameter of the root circle, so the male die of the punching press is pressed against the inner surface of the base of the sprocket teeth. Therefore, the sprocket teeth can be formed by pressing at low cost.

Furthermore, in the present invention, since the outer cylinder body has the same outer diameter as the conventional one, the wall thickness of the outer cylinder body can be made to have the same sufficient strength as the conventional one, and
The screw cover that is screwed onto the core can be secured to a size that is as strong as the conventional one, and as a result, the durability of the outer ball bearing part can be maintained at a high level. .

Furthermore, in the present invention, the first
The radius of the surface of the ball receiver is the same as the second one formed on the inner periphery of the outer cylinder body.
Since the ball bearing is made smaller than the radius of the surface by an amount corresponding to the tooth bottom height mentioned above, the wall thickness of the inner cylinder body can be made to have sufficient strength to be almost the same as the wall thickness of the outer cylinder body. It can be made into different dimensions.

In addition, in the present invention, the surface of the first ball holder and the surface of the third ball holder that is opposite to each other are also largely hollowed out in the core, and the height in the radial direction of the steel ball contacting part at the bottom is formed into a screw cap. The fourth ball bearing has a dimension smaller than the radius height of the steel ball abutting portion of the surface, which corresponds to the tooth bottom diameter, so that the first ball bearing and the third ball bearing are interposed between the surface and the third ball bearing. As the steel balls to be inserted, a sufficiently large steel ball can be used, as is the steel ball to be inserted between the surface of the second ball holder and the surface of the fourth ball holder.

Furthermore, since the third ball holder is formed on the core itself, although the surface is largely hollowed out, the thickness of the core in this area is also sufficient, which actually contributes to reducing the weight of the core.

For this reason, the durability of the inner ball bearing part can be as sufficient as that of the outer ball bearing part.

As a result of the above, a bicycle freewheel that can reduce the sprocket diameter, form the sprocket teeth at low cost, and has sufficient rotational performance and durability has been developed.

[Explanation of Examples]

Hereinafter, embodiments of the bicycle freewheel of the present invention will be specifically described with reference to the drawings.

The free gear body 1 includes a sprocket tooth portion 2 formed approximately in the middle in the axial direction on its outer periphery, an inner cylindrical body portion 3 inward from the sprocket tooth portion 2, and an outer cylindrical body portion 3 outward from the sprocket tooth portion 2. It has a cylinder body part 4.

As shown in detail in FIG. 3, the teeth of the sprocket tooth portion 2 are:
so that a constant tooth root height is formed, i.e. the tooth root is at a predetermined height with respect to the area adjoining the inner barrel 3 and the sprocket teeth outwardly, i.e. at least the radius of the roller of the roller chain. and the maximum radius of the ring plate.

The radius of the outer periphery of the portion where the sprocket teeth 2 are formed or the inner cylinder body 3 is smaller than the radius of the outer periphery of the outer cylinder body 4 by approximately the height of the tooth bottom.

The sprocket teeth of a conventional freewheel are
Since it is formed on the cylinder body having the same outer diameter as the above-mentioned outer cylinder body of the present invention, the sprocket diameter of the freewheel of the present invention is approximately at the root height above the sprocket diameter of the conventional sprocket. The size is reduced by twice the size.

A first ball bearing surface 5 is formed on the inner periphery of the inner cylinder body 3, a second ball bearing surface 6 is formed inside the outer cylinder body 4, and a second ball bearing surface 6 is formed on the inner periphery of the intermediate portion. Ratchet teeth 7... are formed.

The radius of the surface 5 of the first ball bearing is the same as the height of the tooth root mentioned above.
The radius of the ball bearing is smaller than the radius of the surface 6, thereby making the wall thickness of the inner cylinder body 3 as sufficient as that of the outer cylinder body 4.

The free gear body 1 formed as described above is supported by the core 8 so as to freely rotate in one direction.

This core 8 has a female screw 9 on its inner periphery which is screwed onto a not-shown bubble body, and on its outer periphery, the first ball holder is diagonally opposed to the surface 5, the third ball holder is oriented diagonally to the surface 10, and the ratchet is connected to the ratchet. Tooth 7...
・It has a ratchet pawl support portion 11 facing the ratchet pawl, and a small diameter male screw portion 14 on the outer side.

A screw lid 13 is screwed onto the small diameter male screw portion 14, and the second ball bearing is attached to the surface 6 on the outer periphery of the screw lid 13.
A surface 12 is formed on the fourth ball receiver which faces diagonally.

And between the first ball receiver and the surface 5 and the third ball receiver and the surface 10,
Groups of steel balls 16 . . . , 19 . . . are removably interposed between the surface 6 of the second ball holder and the surface 12 of the fourth ball holder.

Further, as shown in FIG. 2, one ratchet pawl 17 or a desired side of the ratchet pawl 17 is semi-buried in the ratchet pawl support portion 11 while being always biased in the upright direction by a ring spring 18.

The surface 10 of the third ball bearing is formed by shaving the outer periphery of the inner part of the core 8 inward in the radial direction to have a semicircular arc shape in cross section, and the radius of the steel ball contacting part of the bottom 10a is as described above. The fourth ball receiver formed on the screw cap 13 is designed to have a dimension smaller than the radius of the steel ball abutting portion of the surface 12, which corresponds to the height of the tooth bottom.

As a result, the distance between the surface 5 of the first ball receiver and the surface 10 of the third ball receiver is as wide as the distance between the surface 6 of the second ball receiver and the surface 12 of the fourth ball receiver. The steel ball 16 should be interposed between the surface 5 of the ball holder and the surface 10 of the third ball holder...The steel ball 16 should be interposed between the surface 6 of the second ball holder and the surface 12 of the fourth ball holder. It becomes possible to use a steel ball with the same large diameter as the steel ball to be inserted.

As described above, the surface 10 of the third ball holder is largely carved inward in the radial direction, but since the surface 10 of the third ball holder is formed on the core itself, the bottom 1
The wall thickness between Oa and the female thread 9 on the inner periphery is still sufficient, which actually helps to reduce the weight of the core 8.

Note that reference numeral 20 is interposed between the screw lid 13 and the outer wall 11b of the ratchet pawl support portion 11 to adjust the adjustment of the pair of inner and outer ball bearings P and Q. Shows the tone board for

For this reason, the bearing part P formed on the inner part has the same performance and durability as the bearing part Q formed on the outer part, and as a whole, the freewheel of the present invention has the following characteristics: The rotational performance of the free gear body is maintained at a high level, and the durability is high.

Furthermore, as is clear from FIGS. 2 and 3, since the male die of the press can be brought into contact with the base of the inner side surface of the sprocket tooth portion 2, the sprocket tooth portion in the present invention is
It can be formed at low cost using a punching press.

[Brief explanation of drawings]

Fig. 1 is a partially sectional side view showing one embodiment of the present invention;
The figure is a partially sectional front view, FIG. 3 is an enlarged view of the main part, and FIG. 4 is a partially sectional side view showing a conventional example. 1...Free gear body, 2...Sprocket teeth, 3...Inner cylinder body, 4...
Outer cylinder body, 5... The first ball receiver is a surface, 6...
...The second ball receiver is Men, 8... Nakago, 10...
...The third ball receiver is a face, 12...The fourth ball receiver is a face, 1
3...Screw lid, 16...Steel ball group, 19
....Group of steel balls.

Claims (1)

[Scope of utility model registration request] A free gear body is provided with sprocket teeth on the outer periphery of the axially intermediate part, a first ball bearing has a surface on the inner periphery of the axially inner part, and a second ball bearing has a surface on the inner periphery of the axially outer part, and The third ball holder has a surface on the outer periphery of the core, and the fourth ball holder has a surface on the outer periphery of the screw lid screwed on the axially outer part of the core.
A group of steel balls is interposed between the surface of the first ball holder and the surface of the third ball holder, and between the surface of the second ball holder and the surface of the fourth ball holder, respectively, so as to be transferable. In the bicycle freewheel rotatably supported by the free gear body, the outer periphery of the inner cylindrical body portion inward from the sprocket tooth portion and the outer periphery of a portion of a predetermined length adjacent to the outside of the sprocket tooth portion of the free gear body. The radius of the second ball bearing is approximately equivalent to the height from the base of the sprocket tooth to the bottom of the sprocket tooth relative to the radius of the outer periphery of the outer cylinder body located radially outside the surface. In addition to reducing the dimensions, the first ball bearing has a radius of the surface, and the second ball bearing has a dimension corresponding to the difference in radius between the outer periphery of the inner cylindrical body and the outer periphery of the outer cylindrical body. The wall thickness of the inner cylinder body is made equal to that of the outer cylinder body by reducing the size, while the third ball bearing has a cross section radially inward from the outer peripheral surface of the outer part of the core. The fourth ball holder is hollowed out into a substantially semicircular arc shape, and the radius of the steel ball contacting part at the bottom thereof is set so that the radius of the steel ball contacting part of the fourth ball holder is the same as the radius of the steel ball contacting part of the surface of the fourth ball holder. A bicycle freewheel characterized by a ball holder whose size is reduced to correspond to the difference in the radius of the surfaces.