JPH0340714Y2 - - Google Patents

Description

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

This invention relates to belt-driven bicycles, and is an improvement that prevents the belt from separating from the rear gear at the belt entry point of the rear gear due to belt stretching, and prevents the belt from skipping teeth. related to things.

[Prior art and its problems]

Recently, bicycles equipped with a belt drive mechanism instead of a chain drive mechanism have become popular. This type of bicycle usually has a toothed endless belt made of rubber containing a core material, a front gear around which this belt is suspended,
and a rear gear. In this case, the tooth widths of the front and rear gears are set to correspond to the belt width, and flanges are provided on both sides of the gears to prevent the belt from falling off. The shape of the teeth of the belt is set according to the shape of the teeth of the front and rear gears, and depending on the type of bicycle, a freewheel is adopted as the rear gear. The driving force from the pedal is then transmitted to the front gear, and the rotation of the belt rotates the rear gear. By the way, as mentioned above, the belt on the above bicycle is made of rubber, so when a sudden pedal force is applied to the pedal, a huge tension is applied to the part that runs between the upper end of the rear gear and the upper end of the front gear, causing tension in this part. elongation occurs. This causes a change in the overall length of the endless belt, causing slack in the part that runs between the lower end of the front gear and the lower end of the rear gear, but the following phenomenon also causes tooth skipping in the rear gear. cause In other words, the enormous tension that acts between the upper end of the rear gear and the upper end of the front gear affects the parts that are wrapped around each of the front and rear gears. Due to the impact, a force acts to pull the belt part wrapped around the rear gear upwards, and as a result,
At the point where the belt enters the rear gear, the belt lifts up from the rear gear compared to a normal belt hanging state. If the above-mentioned lifting phenomenon occurs at the part that is about to wrap around the rear gear, this lifting phenomenon will instantly spread to the entire part that is wrapping around the rear gear, and eventually the teeth against the rear gear will become loose. This causes the belt to skip teeth. Regarding the front gear, the circumference length around which the belt is wound is greater than that of the rear gear, and strong tension acts on the part where the belt enters the front gear. A flying phenomenon cannot occur. This idea was devised based on the above knowledge, and even when a strong driving force is applied to the pedal, the tooth skipping phenomenon does not occur in the rear gear as in the conventional case. The task is to ensure that there are no.

[Means to solve the problem]

In order to solve the above problems, this invention employs the following technical means. In other words, this invention is based on a belt-driven bicycle in which a toothed endless belt is suspended between the front gear and the rear gear. A bracket having a roller support part located on the outer surface of the belt is fixed to the vehicle body, and a bracket is attached to the roller support part slightly against the outer surface of the belt at the part where the roller support part wraps around the rear gear for a predetermined length from the entrance part. It is characterized by rotatably supporting rollers located apart from each other.

[Functions and effects of the idea]

In the invention of the present invention, a roller located slightly away from the outer surface of the belt is rotated at a portion of the belt that is suspended around the rear gear that wraps around the gear after a predetermined length from the entry point to the rear gear. It is movably supported. Therefore, under normal running conditions, when there is no slack in the belt running between the lower end of the front gear and the lower end of the rear gear, the rollers do not come into contact with the belt and the belt It does not add unnecessary frictional force to driving. On the other hand, if a strong pedal force is applied to the pedals, and a large tension is applied to the part of the belt that runs between the upper end of the rear gear and the upper end of the front gear, this large tension will cause the belt to wrap around the rear gear. After that, the part of the belt that is caught on the gear, or the part that is about to wrap around the rear gear, tends to be torn off from the rear gear. However, in the present invention, as described above, the roller located slightly away from the outer surface of the part where the belt wraps around the rear gear by a predetermined amount from the entry point to the rear gear actually rotates the belt. Thereafter, as the rear gear rotates, it forcibly prevents the rear gear from moving away from the rear gear from the entrance to the gear. Moreover, since the rollers contact the outer surface of the belt while rolling and prevent it from lifting off from the rear gear as described above, the resistance at this time is extremely small and does not cause any trouble in running. As described above, the present invention effectively prevents the tooth skipping phenomenon described above with a simple configuration based on the knowledge regarding the mechanism of the tooth skipping phenomenon in belt-driven bicycles when a strong pedal force is applied. I was able to do so.

[Explanation of Examples]

Hereinafter, embodiments of this invention will be described in detail with reference to the drawings. First, a first embodiment will be explained in detail with reference to FIGS. 1 to 4. The belt-driven bicycle 1 in this example includes a front gear 2, a rear gear 3, and a toothed endless belt 4 that is suspended between the two gears 2, 3. The front gear 2 is configured to transmit rotational force from the pedal 5 to the belt 4, and cooperates with the rear gear 3 to rotate the belt 4. On the other hand, at the belt entry portion of the rear gear 3 (the point where the pitch line of the belt teeth and the pitch circle diameter of the rear gear 3 touch) or a portion that has advanced a predetermined amount in the rotational direction from this point, it is located on the outer surface 4a side of the belt 4. Bracket 7 with curved plate-shaped roller support part 6
is fixed to the vehicle body 8, and is further located on the roller support portion 6 slightly apart from the outer surface 4a at a portion of the belt 4 that has advanced in the direction of rotation of the gear after a predetermined distance from the belt entry portion 3a. Two cylindrical rollers 9, 9 are rotatably supported at a predetermined interval in the longitudinal direction of the roller support section 6. That is, the bracket 7 is attached to the belt 4.
A roller support section 6 consisting of a thin first curved plate 10 placed on the side, and a second curved plate 11 superimposed on this first curved plate 10 and made somewhat thicker than the first curved plate 10. and the belt 4 is connected from one side at one end in the longitudinal direction of the belt 4.
The main body part 12 passes through one side of the rear gear 3 and is fixed to the vehicle body 8. This main body part 12
The tip of the nut 13 penetrates through the vehicle body 8 and is fitted with a nut 13.
A fitting hole 15 is formed into which the tip threaded portion 14a of the hub 14 is to be screwed. That is, in the normal state, the roller 9 is held in a position separated from the belt 4, but only when the belt 4 attempts to separate from the rear gear from the vicinity of the belt entrance part. External surface 4
It is made to come into contact with a. In this case, the belt outer surface 4a of the roller 9
The spacing between the fitting holes 15 and 12 is set by changing the longitudinal dimension of the main body 12 of the bracket 7, but it is also possible to set the fitting hole 15 by allowing some play in the longitudinal direction of the main body 12. It may be formed into a substantially elongated hole shape so that the distance between the holes can be adjusted. In addition,
Since the roller 9 is positioned slightly apart from the outer surface of the belt 4 at the portion where it is wound around the rear gear 5, it is possible to set this distance to be extremely small under normal conditions. However, in reality, it is also possible to position them with almost no spacing between them. Further, the roller 9 is fitted into through holes 16 and 17 formed in the two curved plates 10 and 11, which are stacked on top of each other, respectively.
It is supported so that it can roll. That is, as shown in FIG. 4, the inner diameter of the through hole 16 on the inner surface 10a side of the first curved plate 10 is set smaller than the inner diameter on the outer surface 10b side. The inner diameter of the curved plate 11 on the outer surface 11a side is its inner diameter 11b.
The inner diameter of the roller 9 is set smaller than the inner diameter of the roller 9.
In the fitted state, the through holes 16 to 17
It is supported so that it can rotate inside and cannot fall off. The distance between the rollers 9 is adjusted so that the slack in the belt 4 is effectively corrected and the tooth row on the belt 4 side and the tooth row on the rear gear 3 side are properly engaged. As shown in FIG. 2, at least one of the rollers 9 is always on the belt outer surface 4a.
It is desirable to set it so that it contacts the part 4c corresponding to the bottom part 4b of the tooth. In this case, for example, if the interval between the rollers 9 is set to 1.5 times the pitch of the teeth of the belt 4,
Irrespective of the rotation of the belt 4, any one of the rollers 9 may loosen at its tooth bottom 4 on the outer surface 4a of the belt 4.
This is convenient because it always comes into contact with the part 4c corresponding to b. In this example, a freewheel is employed as the rear gear 3, and the freewheel 18 includes a core 19 fixed to the hub 14 of the rear wheel (not shown), and a plurality of cores attached to the core 19. A sprocket 21 supported for relative rotation via a steel ball 20, the core 19, and the sprocket 2.
1 and a one-way clutch mechanism 22 provided between the two. In this case, the sprocket 21 is connected to the core 19.
Bearing part 23 for allowing relative rotation of
The plurality of steel balls 20 are rotatably interposed between a ball receiving surface 19a formed on the outer periphery of the core 19 and a ball receiving surface 21a formed on the inner periphery of the sprocket 21 at the end near the hub. The first bearing part 24 is equipped with a first bearing part 24, the ball receiving surface 25a formed on the outer periphery of the screw cap 25 at the opposite end thereof, and the sprocket 21.
and a second bearing part 26, in which a plurality of steel balls 20 are also rotatably interposed between the ball receiving surface 21b formed on the inner periphery of the bearing part 26. The one-way clutch mechanism 22 also includes a ratchet pawl 27 semi-embedded in the outer periphery of the intermediate portion of the core 19 so as to be able to swing up and down, and a ratchet tooth 28 formed on the inner periphery of the sprocket 21 facing the ratchet pawl 27. Consisting of: Furthermore, the bicycle 1 is equipped with a chain pulling mechanism 29 for adjusting the tension of the belt 4. In the illustrated example, 30 is a chain pulling bolt, 31 is a chain pulling washer, and 32 is a chain pulling nut. Each is shown below. The operation of the above configuration will be explained with reference to FIG. When a strong pedal force is applied to the pedal 5,
Belt 4 suspended between front gear 2 and rear gear 3
After that, a strong tension is applied to the part running between the upper part of gear 3 and the upper part of front gear 2. This strong tension also affects the parts wrapped around rear gear 3, and as a result,
The part of the belt 4 that enters the rear gear is about to be torn off from the rear gear. This means that the belt 4 tries to lift off from the rear gear 3 at the entrance to the rear gear or at the part where it is already wrapped around the rear gear. A lifting behavior of the belt relative to the rear gear is effectively prevented by the rollers 9. As mentioned in the section on the prior art, if the belt 4 lifts up from the rear gear at the entry point to the rear gear 3 or at a portion that advances in the rotational direction of the rear gear, this phenomenon will occur instantly. This lifting phenomenon spreads to the entire part wrapped around the rear gear 3 due to the strong tension as described above, causing the so-called tooth skipping phenomenon of the belt. According to the invention of the present invention, it is possible to completely prevent the lifting of the belt at the entry point to the rear gear or a portion slightly further forward, which is a primitive phenomenon that extends to the tooth skipping phenomenon. Therefore, the tooth skipping phenomenon described above cannot occur. Incidentally, as in the second embodiment shown in FIG. 5, the bicycle 1 has the roller support section 6 made up of a single plate, and flanges 6a, 6a are provided on both sides of the roller support section 6 along its longitudinal direction. While forming, the roller 9
A guide pin 9b is provided at both ends of the flange 6a, and the guide pin 9b is rotatably supported by the flange 6a.
The roller 9 may be configured to be pivotally supported by the roller support portion 6. By doing so, the frictional resistance generated between the belt outer surface 4a and the roller 9 can be more effectively reduced. Of course, the scope of this invention is not limited to the above embodiments. For example, the number of rollers 9 and the spacing between each roller 9 in the above embodiment are set in accordance with the pitch dimension of the tooth row of the belt 4 so as to effectively prevent the belt 4 from separating from the rear gear 3. It is something that will be done. Furthermore, the configurations of the bracket 7 and roller 9 are not particularly limited to those shown in the illustrations, and for example,
The roller 9 may be spherical. It goes without saying that the bicycle 1 described above can be modified in various other ways within the scope of the present invention.

[Brief explanation of the drawing]

Figure 1 is a front view showing the first embodiment of this invention;
Figure 2 is an enlarged cross-sectional view of the main part, Figure 3 is a cross-sectional view taken along the - line in Figure 2, and Figure 4 is a - line in Figure 3.
FIG. 5 is an enlarged cross-sectional view taken along a line showing a second embodiment of this invention. 1...Belt-driven bicycle, 2...Front gear, 3
...Rear gear, 3a...Belt entrance part, 4...Toothed endless belt, 4a...Belt outer surface, 6...Roller support part, 7...Bracket, 8...Car body, 9...
…roller.

Claims (1)

[Scope of Claim for Utility Model Registration] In a belt-driven bicycle in which a toothed endless belt is suspended between the front gear and the rear gear, the belt that is suspended around the rear gear passes from the entry point to the rear gear to the rear gear. A bracket having a roller support part located on the outer surface of the belt around the part where the belt is wound is fixed to the vehicle body, and a bracket with a roller support part located on the outer surface of the belt from the entry part to the rear gear for a predetermined length is attached to the roller support part. A belt-driven bicycle characterized in that rollers positioned slightly apart from each other are rotatably supported.