JPH0231610Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a mechanism for preventing rotation of an adjustment bolt, and more specifically, to a mechanism configured to securely hold an adjustment bolt at a desired screw advance position. .

[Conventional technology]

Generally, the range of movement of a movable body is regulated by screwing an adjustment bolt having an abutting end into a screw hole so as to be movable back and forth. By changing the amount of screwing of the adjustment bolt, the axial position of the tip abutting portion changes, so the movement range of the target moving object can be changed or adjusted.

For example, a bicycle external derailleur
In the above, a pantograph link mechanism is constituted by a fixed member fixed to the bicycle frame, a movable member including a chain guide member, and a pair of link members connecting the fixed member and the movable member. A pair of adjustment bolts is screwed into one of the two members, and each regulation piece that abuts the pair of adjustment bolts is provided on each of the other two members that move relative to this member.

The amount of deformation of the pantograph link mechanism, that is, both ends of the movement range of the chain guide member is defined by the pair of adjustment bolts hitting each of the regulating pieces. Therefore, when the amount of screwing of the adjustment bolt is changed, the range of deformation of the pantograph link mechanism changes, and accordingly, the range of movement of the chain guide member changes.

However, the above method of adjusting the movement range of the chain guide member in an external transmission has the following problems.

Since the pair of adjustment bolts mentioned above are simply screwed together so that they can move forward and backward into one member, they will gradually loosen due to repeated collisions with each regulation piece and vibration, etc. The correct spiral position is lost. Therefore, the movement range of the chain guide member changes over time, resulting in deterioration of the speed change performance of the transmission.

As an idea to temporarily solve this problem, as shown in Utility Model Publication No. 52-51400, the upper half of the rectangular stop made of synthetic resin has a diameter larger than the outer diameter of the adjustment bolt. In addition to providing two insertion holes, two fastening holes that are concentric with the insertion hole and have a smaller diameter than the outer diameter of the adjustment bolt and a fitting gap for fitting the bolt mounting plate are provided in the lower part,
There is an adjustment bolt rotation prevention structure constructed by fitting this stopper into a bolt mounting plate and screwing the adjustment bolt into a fastening hole of the stopper or a screw hole of the bolt mounting plate. In such a structure, a large frictional force is generated between the bolt that is forcibly screwed into the small-diameter fastening hole and the fastening hole, so this frictional force prevents the adjustment bolt from loosening and rotating. The screwed position of the bolt is maintained for a long period of time.

[Problem that the invention attempts to solve]

However, the adjustment bolt rotation prevention structure disclosed in the above-mentioned publication also has the following problems.

In other words, in addition to insertion holes and fastening holes with different diameters, in order to form a gap in the stopper body into which the bolt mounting plate fits, the stopper body must be processed in a complicated manner. is troublesome and complicates the production process. Since there are only limited cases in which a stopper with such a complicated structure can be combined with a bolt mounting plate, the scope of application is considerably limited.

This idea was devised under the above circumstances; it has a simple structure, is easy to manufacture and assemble, and has a design around the adjustment bolt that can be used in a very wide range of applications. The task is to provide a stopping mechanism.

[Means to solve the problem]

In order to solve the above problem, this invention takes the following technical measures.

That is, it is a detent mechanism that holds an adjustment bolt screwed into a screw hole at a desired screw advance, and a counterbore is formed at the end of the screwhole, while the inner diameter of the counterbore in the natural state. A detent member that has a larger outer diameter, a center hole for holding an adjustment bolt, and is formed to be able to sufficiently elastically contract by providing a cut groove that connects from the outer periphery to the center hole is elastically compressed. The adjustment bolt is fitted into the counterbore portion in a relatively unrotatable manner while adjusting the diameter thereof, and the adjustment bolt is forcibly inserted into the center hole whose diameter has been reduced so that the inner diameter is smaller than the threaded diameter of the adjustment bolt. It is screwed together.

[Effect]

In this invention, a detent member that is elastically contractible and has a central hole for holding an adjustment bolt is attached to a counterbore provided at the end of the screw hole to accommodate the detent member, so that it cannot rotate relative to the detent member. After fitting, the adjustment bolt is screwed into the rotation preventing member and the screw hole to a desired screw position.

That is, in order to facilitate elastic compression, a cut groove is provided from the outer periphery to the center hole, and the outer diameter is larger than the inner diameter of the counterbore in the natural state, and the center becomes smaller than the mountain diameter of the adjustment bolt when the diameter is elastically reduced. The anti-rotation member provided with the hole is fitted into the counterbore portion while being elastically reduced in diameter, and the adjustment bolt is screwed into the center hole while making a thread, so that the center hole and It is screwed into the screw hole.

The threading surfaces of the center hole and the adjusting bolt strongly engage with each other due to the viscoelasticity of the rotation preventing member, and a very large frictional force is generated between the two. Therefore, this frictional force prevents the adjustment bolt from rotating, and the screwed position of the adjustment bolt is maintained for a long period of time.

〔effect〕

Therefore, the anti-rotation member uses its strong elastic force and viscous force to fix the adjustment bolt and prevent it from rotating, so even if impact force, vibration, etc. are applied to the adjustment bolt, the adjustment bolt will not move. The screw position is reliably maintained.

In addition, it is only necessary to form a counterbore with a predetermined inner diameter on a member with a screw hole, and the anti-rotation member can be made from a plate member that can be elastically deformed by press punching. The process is simple and very cost-effective.

Moreover, the anti-rotation member is housed and held in the counterbore by its elastic force simply by fitting it into the counterbore in a state in which its diameter is elastically contracted, so no special fixing means is required to fix it. Therefore, the assembly workability is greatly improved.

Furthermore, since the detent member can elastically contract in diameter steplessly within the range allowed by the kerf, by changing only the diameter of the counterbore portion and changing the amount of diameter reduction of the detent member, the same detent member can be can be used as a detent mechanism for adjusting bolts of various diameters.

[Explanation of Examples]

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings of FIGS. 1 to 5.

In this example, the present invention is applied to an adjustment bolt for adjusting the deformation range of a pantograph link mechanism of a rear derailleur of a bicycle.

A pair of screw holes 3, 3 are bored in the adjustment bolt mounting plate 4, which is normally formed integrally with the outer link, and a counterbore with a predetermined inner diameter and a predetermined depth is provided at one end of these screw holes 3, 3. Parts 2, 2 are formed. That is, the inner diameter of the counterbore portions 2, 2 is set to be smaller than the outer diameter in the natural state of the detent members 1, 1, which will be described later, and the depth is at least equal to the thickness of the detent members 1, 1. It is said to be more than that. Also,
Concave grooves 2a, 2a for preventing rotation of the detent members 1, 1 fitted inside the counterbores 2, 2 are formed at appropriate inner circumferential portions of the counterbores 2, 2.

On the other hand, the anti-rotation members 1, 1 are approximately donut disk-shaped members made of an elastically deformable material such as synthetic resin, and have an outer diameter larger than the inner diameter of the counterbore in their natural state. By forming the kerfs 1c, 1c provided so as to connect the outer periphery and the center holes 1a, 1a, the range allowed by the distance between the kerfs 1c, 1c, as shown in FIGS. 4a and b. It is designed to be able to contract sufficiently elastically. In addition, the sizes of the center holes 1a, 1a are as follows:
When the anti-rotation members 1, 1 are fitted into the counterbore portions 2, 2 and elastically contracted in diameter, they are set to be smaller than the thread diameter of the adjustment bolts 6, 6. moreover,
Protrusions 1b, 1b that engage with grooves 2a, 2a formed in the counterbore portions 2, 2 are provided on appropriate portions of the outer peripheries of the anti-rotation members 1, 1.

As shown in Fig. 5a, the counterbore portion 2,
anti-rotation member 1 having an outer diameter larger than the inner diameter of 2;
1 is fitted into the counterbore portions 2, 2, the detent members 1, 1 become elastically reduced in diameter, and at this time, as shown in FIG. 5b, the center holes 1a,
1a is also reduced in diameter, and its inner diameter becomes smaller than the crest diameter of the adjustment bolt 6, that is, the trough diameter of the screw holes 3, 3. Then, the center hole 1a whose diameter has been reduced in this way,
Adjustment bolts 6, 6 are screwed into 1a or the screw holes 3, 3. At this time, the adjustment bolts 6, 6 thread through the inner walls of the reduced diameter center holes 1a, 1a while forcibly and elastically expanding the center holes 1a, 1a.
A strong engagement occurs between a and the threads of the adjusting bolts 6, 6, and a large frictional force is generated between them, and this frictional force acts as a force to prevent the adjusting bolts 6, 6 from loosening and rotating.

Therefore, the adjustment bolts 6, 6 are reliably held by the frictional force when they are screwed to a desired amount, and even if some external force or impact is repeated, the screws will not advance. The position will not go out of order,
The deformation range of the pantograph link mechanism, i.e.
The adjusted movement range of the chain guide member will not go out of order over time. Furthermore, since the rotation preventing member only needs to be elastically fitted into the counterbore formed at the end of the screw hole of the adjustment bolt mounting plate, the installation work is extremely simple. In addition, since the above-mentioned counterbore portion is fitted with a detent member whose diameter is sufficiently elastically reduced by having a cut groove, a high degree of machining accuracy is not required for the counterbore portion and the detent member.
The manufacturing process is simplified.

Of course, the scope of this invention is not limited to the embodiments described above.

For example, the specific shape of the anti-rotation member, the corresponding counterbore, and the means for making these relative non-rotatable can be modified in various ways other than the above embodiments.

In addition, by changing the size of the cut groove of the detent member, it is possible to obtain various diameter sizes of the center hole for holding the adjustment bolt during elastic diameter contraction, thereby allowing adjustment of various outside diameters. Since it is compatible with bolts and has a simple structure, it can be used for a wide range of purposes other than the bolt for adjusting the deformation range of the pantograph link mechanism in a rear derailleur. For example, it can be applied not only to a bolt for adjusting the deformation range of a link mechanism of a front derailleur, but also to a bolt for adjusting the length of the outer tube end of a cable for operating these derailleurs and brakes.

[Brief explanation of drawings]

Fig. 1 is a front view of an embodiment of the present invention, Figs. 2 and 3 are explanatory diagrams of main parts of the embodiment, Fig. 4 is a front view of a rotation prevention member in the embodiment, Figs. 5 a, b,
c is an explanatory diagram of the operation of the embodiment. DESCRIPTION OF SYMBOLS 1... Anti-rotation member, 1a... Center hole for holding adjustment bolt, 2... Counterbore, 3... Screw hole, 6...
adjustment bolt.

Claims (1)

[Scope of utility model registration request] It is a rotation prevention mechanism that holds an adjustment bolt screwed into a screw hole at a desired screw advance amount, and a counterbore is formed at the end of the screwhole, and the inner diameter of the adjustment bolt is larger than the inner diameter of the counterbore in its natural state. A detent member is provided with an outer diameter and a center hole for holding an adjustment bolt, and is formed so as to be able to sufficiently elastically reduce its diameter by providing a cut groove that connects from the outer periphery to the center hole. while fitting into the above counterbore so that relative rotation is impossible,
An adjustment bolt rotation prevention mechanism characterized in that the adjustment bolt is forcibly inserted into the center hole whose diameter is reduced so that the inner diameter is smaller than the threaded diameter of the adjustment bolt, and the adjustment bolt is screwed into the threaded hole. .