JPS642556B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an external chain guide for rear speed gear devices of bicycles and similar vehicles. Speed gear devices equipped with this chain guide naturally also fall within the scope of the invention.

The present invention relates to the technical field of accessories and equipment for bicycles and similar vehicles.

Rear speed gear devices for bicycles etc. are mainly
It consists of a parallelogram system or a system with sliding pins or the like for laterally displacing a chain guide connected to a stepped sprocket integral with the hub of the rear wheel.

A chain guide generally consists of a cheek (close to the frame) and a counter cheek (away from the frame) between which one or more rollers are mounted for free rotation. A chain is wrapped around it to keep it stretched. Cheeks and counterteaks are generally made from metal, especially from light alloys, by metal cutting operations, often stamping.

The cutting-stamping production of metal cheeks is not without drawbacks, for example due to the fact that during the production of the teak some dimensional changes occur due to tool misadjustments. This results in expensive waste and
Problems may arise during work.

It is also possible to make the cheek from plastic, but in this case, a threaded groove or groove is provided inside the cheek so that it can be screwed onto the part where strength is required, that is, the tip of the pin for pivotally supporting the roller. In order to screw into the pin for coupling to the chain guide rotation device of the transmission, it is necessary to reinforce the thread groove provided inside the cheek. For this purpose, the thickness of the cheek near these thread grooves may be increased, but it is preferable to further increase the reinforcing effect and to eliminate the increase in weight of the chain guide due to the increase in the thickness of the cheek.

An object of the present invention is to provide a bicycle that is light in weight while having sufficient strength by embedding a metal female screw inside the cheek, and that can prevent dust from adhering to the pins that support the rollers. An object of the present invention is to provide a chain guide for an external transmission.

The object of the present invention is to provide a chain guide for an external transmission of a bicycle, which comprises: a disc-shaped first roller for guiding the chain; a first pin that pivotally supports the first roller; a first plastic side plate supporting one end of the first pin;
A second side plate made of plastic is disposed parallel to and opposite to the first side plate, and a pin is embedded inside the second side plate to reinforce the second side plate. a first female thread made of metal that is screwed onto the end;
One end is supported by the first side plate, and the other end is supported by the second side plate.
It is screwed onto a second female screw made of metal embedded inside the second side plate in order to reinforce the side plate of the The roller is supported by a disc-shaped second roller for guiding the chain, one end is configured to be coupled to a chain guide rotation device of a transmission, and the other end is coupled to a first side plate. A third pin that is screwed into a third internal metal screw embedded inside the first side plate for reinforcement, and a chain guide whose one end is screwed into a threaded groove provided inside the first side plate. a fourth pin for rotation restriction; a first annular protrusion provided on the inner surface of the first side plate and extending in the axial direction of the first pin so as to cover the first pin; a second annular projection provided on the inner surface and extending in the axial direction of the first pin so as to cover the first pin; and a second annular projection provided on one side of the first roller to receive the first annular projection. a first annular groove provided on the other side surface of the first roller to receive the second annular protrusion; 2nd pin so as to cover the 2nd pin
a third annular projection extending in the axial direction of the pin;
a fourth annular projection provided on the inner surface of the side plate and extending in the axial direction of the second pin so as to cover the second pin; and one side surface of the second roller for receiving the third annular projection. a third annular groove provided in;
a fourth annular groove provided on the other side of the second roller to receive the fourth annular protrusion; the fourth annular groove is provided inside the first side plate; This is achieved by a chain guide characterized in that the thickness of the portion surrounding the thread groove to which the chain guide is attached is greater than the thickness of the other portion of the first side plate.

The cheeks, or side plates, of the chain guide of the present invention use female metal threads embedded inside the side plates, so they are lightweight while having sufficient strength.

Furthermore, since it is possible to prevent dust and the like from adhering to the pins that pivotally support the rollers, it has excellent durability.

For a better understanding of the object of the invention without limitation, reference is made to the attached drawings.

Figure 1 shows the rear part of the bicycle frame, especially the
The ends of the base B and the brace H supporting the fixed lug P of the hub M of the rear wheel together with the wheel R are shown. A parallelogram-shaped speed gear device V is attached to the rear wheel axis A by means of lugs _V1 , etc.

The illustrated speed gear device mainly consists of an upper yoke V 2 connected by two small rods V ₄ -V ₅ to form a strained parallelogram for moving the chain C laterally with respect to the axis of the _wheel.
and lower yoke V ₃ .

Other elements, such as guides and fixing elements for the control cables and elements for adjusting the amount of movement, are also provided in a known manner.

Pin V ₆ is inserted into the lower yoke V ₃ ,
A coil spring concentric with the pin is located inside the yoke.

The chain guide according to the present invention includes a cheek 1 and a counter cheek 2 as side plates. The cheek 1 is supported by a pin V ₆ inserted into the lower yoke, and the protruding portion of the pin V ₆ has a threaded portion for engaging with the counternut V ₈ as shown in FIG. _V7 is provided.

The counter cheek 2 is connected to the cheek 1 via two screws 3 as pins that pivotally support the rollers G ₁ and G ₂ respectively.
is connected to.

The apertured cheek 1 and counter cheek 2 of the invention are manufactured accurately and economically from plastic. The plastic must be of a high quality such as acetate resin.

The use of plastics to manufacture the cheeks and counter-cheeks allows for different shapes of the sections of the various parts according to installation and operational needs.

The counter cheek 2 has a central portion 2a reinforced by a thicker raised portion of the material (FIG. 3, the portion drawn with parallel lines).

As clearly shown in FIGS. 4 to 7, the thickness of the counter cheek 2 gradually increases toward the center.

This reinforced central portion 2a corresponds to the extrusion surface of the chain when the chain guide is spaced from the frame and the chain is moved onto a smaller diameter freewheel sprocket. The cheek 1 also has a similar section for pushing out the chain when the chain guide is moved towards the frame and the chain is moved onto a larger diameter freewheel sprocket. It is understood that this raised portion of material is located on the outer surface of the cheek and counter cheek.

As understood from FIGS. 8, 9, and 11, the female thread is reinforced by increasing the number of threads of the female thread that can be screwed onto the screw 3 by means of the reinforcing portion 2b.

The internal thread for the screw 3 can be economically obtained directly from the molding without the need for post-machining drilling. screw 3
The internal threads for the screws are automatically bored and the self-braking function of the screws is provided by the clamping action of the plastic.

As shown in FIG. 11, the number of threads of the female thread that can be screwed into the screw 3 is further increased by providing the cylindrical portion 2c projecting from the female thread. In this case, the shaft spacer 4 inserted between the screw 3 and the roller G ₁ or G ₂ is provided with a chamber ring 4 a for receiving the cylindrical portion 2 c. It is understood that the cylindrical part 2c can also be provided as an alternative to the reinforced central part 2a.

Another feature illustrated in FIGS. 9 and 10 makes it possible to provide the dust cover 5 as an annular projection received in an annular groove G ₃ provided on the side of the roller.

For this purpose, the dust cover 5 is provided with an obliquely bent tear-force-resistant tongue 5b for being embedded in the thickness of the cheek and counter-cheek.

Another feature of the plastic cheek and counter cheek is that the metal insert dust cover 5 is omitted and replaced by cups 1d, 2d which are made when the cheek and counter cheek are molded in one piece. is intended (Fig. 11), and the cup is inserted into the annular groove G ₃ of the roller.
Collaborate with The chain guide according to the present invention includes:
As shown in FIG. 12, the counter cheek 2
embedded with a metal internal thread 6 in the form of a sheet metal washer that is threaded together with the plastic counter cheek with a special threading screw (of the "Parker" type) or an automatic cutting screw during the molding of the With such a configuration, an even greater reinforcing effect can be obtained when the above-mentioned reinforcing portion 2b is provided.

In this case, the spherical cup-shaped reinforcing portion 2b can be omitted, making it possible to reduce the weight of the cheek.

In addition, in order to ensure strong and reliable locking between the cheek 1 and the pin V ₆ , a shoulder nut 8 as a female metal screw inserted into the cavity 1a and the pin V are inserted into the cavity 1a as shown in FIG. By screwing the threaded portion _{V 6} and the threaded portion V ₇ , a large reinforcing effect as described above and a reduction in the weight of the cheek can be obtained. Screw shoulder 8a
is given as a polygon for angle determination.

As seen in Figure 13, the countertop _V8
protrudes relative to the cheek 1, so that automatic braking occurs due to the elasticity of the plastic.

Adjacent to the coupling pin V ₇ of the chain guide and on the outside of the cheek 1 is fixed a pin 9 intended to act as a rotation-limiting stop for the lower yoke V ₃ of the speed gear device of the chain guide. (Figure 13). The pin 9 is threaded directly into a smooth hole in the cheek 1 with a raised portion 3c similar to the previously described raised portion to increase the number of threads to engage. There is thus a tightening of the plastic around the threads, resulting in automatic braking.

It is noted that the thickness of the lower part of the cheek can be reduced to facilitate escape of the chain when the chain is not parallel with respect to the side of the sprocket wheel.

On the other hand, when replacing rollers in order to cooperate with chains of various lengths, it is possible to correspond to various rollers by changing the distance adjusting washer connected to the shaft spacer 4.

Advantages of embodiments of the invention are discussed below.

- Economy due to forming without milling and other machining operations - Stability of dimensional accuracy - Possibility to increase the thickness of the working parts, especially the threaded parts, and reduce run-out areas of the chain - Very wide and rounded Protection of the spokes of the rear wheel against unexpected contact of the counter cheek due to the raised area - Simplicity and speed of installation of a metal dust cover integrated with the cheek and counter cheek or formed directly during molding - cheek Lighter cheeks due to the use of internally embedded metal female threads - No wear and tear on the chain due to chain guides - Prevention of corrosion protection coatings - Noise-free operation - No plastic on the threads Automatic braking of the screw by elastic action - the possibility of providing a curved edge of small thickness to protect against possible contact of the counter cheek with the spokes of the wheel (this curved edge is also disclosed in patent no. 2225327 in the name of the applicant) patent claimed)
, and thus only the bent edges break in the most unfavorable case, preventing spoke breakage.

As described above, the chain guide of the present invention has a structure in which a metal female screw is embedded inside the cheek, so it has the advantage of having sufficient strength and being lightweight.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a non-limiting example of a rear speed gear device mounted on the shaft of the rear wheel of a bicycle, in which the cheek of the chain guide and the counter cheek are shown by solid lines, and the cheek of the chain guide is shown by a solid line. The figure is an explanatory diagram of the chain guide in Figure 1 viewed from arrow F, and
4, 5, 6 and 7 are respectively 4-4 and 5- of FIG. 3 showing various parts of the counter cheek. 5, 6-6, 7-7 lines; FIGS. 8 and 9 are enlarged sectional views illustrating an example of roller attachment between a molded cheek and a molded counter cheek; Figure 10 is a front view showing a dust cover cap adapted to cooperate closely with the counter cheek shown in Figure 9; Figure 11 is an enlarged section showing an example of a molded counter cheek showing the mounting area for the rollers; 12 is an enlarged partial sectional view showing a specific example of a counter cheek showing a portion where a roller is attached according to the present invention; FIG. 13 is a cheek showing a portion where a speed gear device is attached to a lower yoke according to the present invention. It is an enlarged partial sectional view showing a specific example. V...speed gear device, _V2 ...upper yoke, _V3 ...lower yoke, _V4 , _V5 ...rod,
C...Chain, V ₆ ...Pin, _G1 , _G2 ...Roller, 1...Cheek, 2...Counter cheek, 3...
...Screw, 4...Shaft spacer, 5...Dust cover.

Claims (1)

[Scope of Claims] 1. A chain guide for an external transmission of a bicycle, which comprises a disc-shaped first roller for guiding the chain, a first pin that pivotally supports the first roller, and a first roller for guiding the chain. , a first side plate made of plastic that supports one end of the first pin, a second side plate made of plastic disposed parallel to and opposite to the first side plate, and in order to reinforce the second side plate, A first female screw made of metal is embedded inside the second side plate and screwed onto the other end of the first pin, one end is supported by the first side plate, and the other end is supported by the second pin. It is screwed onto a second female screw made of metal embedded inside the second side plate in order to reinforce the side plate of the The second roller is supported by a disc-shaped second roller for guiding the chain, one end is configured to be coupled to a chain guide rotating device of a transmission, and the other end is coupled to a first disc-shaped roller for guiding the chain.
a third pin screwed into a third female screw made of metal embedded inside the first side plate to reinforce the side plate; and one end screwed into a screw groove provided inside the first side plate. a fourth pin for limiting rotation of the chain guide; a first annular projection provided on the inner surface of the first side plate and extending in the axial direction of the first pin so as to cover the first pin; a second annular projection provided on the inner surface of the side plate and extending in the axial direction of the first pin so as to cover the first pin; and one side surface of the first roller for receiving the first annular projection. a first annular groove provided on the first roller; and a second annular groove provided on the other side of the first roller to receive the second annular protrusion.
a third annular projection provided on the inner surface of the first side plate and extending in the axial direction of the second pin so as to cover the second pin; and a third annular protrusion provided on the inner surface of the second side plate. a fourth annular protrusion extending in the axial direction of the second pin so as to cover the second pin; and a third annular protrusion provided on one side of the second roller to receive the third annular protrusion. and a fourth annular groove provided on the other side of the second roller to receive the fourth annular protrusion, the fourth annular groove is provided inside the first side plate, and A chain guide characterized in that a thickness of a portion surrounding the thread groove into which the No. 4 pin is screwed is greater than a thickness of the other portion of the first side plate. 2. The chain according to claim 1, wherein the first to fourth annular projections are each integrally provided with a tongue piece to be embedded in the inner surface of the side plate. guide. 3. The chain guide according to claim 1, wherein the first to fourth annular protrusions are each integrally provided on the inner surface of the side plate by molding.