JPH0159951B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a continuously variable transmission for a bicycle, which is suitable as a transmission mounted on the crankshaft of a bicycle.

(Prior art) As this type of continuously variable transmission, for example,
There is a device disclosed in Japanese Patent No. 54-93754, which is installed on a rear wheel hub axle of a two-wheeled vehicle.

(Problems to be Solved by the Invention) However, since bicycles generally increase the speed of rotation of the crankshaft and transmit it to the rear wheel, the crank gear has a large diameter and the rear wheel sprocket has a small diameter. However, when the above-mentioned transmission is installed on the rear wheel hub axle, the diameter of the rear wheel sprocket increases to a certain extent, and the diameter of the crank gear must also be increased accordingly, resulting in the problem of an increase in the size of the transmission device. It was hot.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to install a continuously variable transmission device on the crankshaft of a bicycle, thereby downsizing the transmission device as a whole, and also to always connect each planetary gear to the sun gear. The purpose of this is to reduce vibrations in the transmission system by press-contacting them.

(Structure of the Invention) In order to achieve the above object, in the present invention, a carrier is fixed to the crankshaft of a bicycle, a plurality of shafts are arranged on the same circumference of this carrier, and a planet is attached to each of these shafts. a planetary gear is fitted to each of these planetary nuclei via a one-way clutch so as to be rotatable in only one direction, and a sun gear integral with the crank gear is mounted on the crankshaft. is provided eccentrically and rotatably with respect to the crankshaft, and is biased so that each of the planetary gears is always in pressure contact with the sun gear, thereby configuring a continuously variable transmission for a bicycle.

(Example) An example of the present invention will be described below with reference to the drawings. In the diagram, 1 is the main pipe of the bicycle frame, 2
A vertical pipe, 3 a chain stay, 4 a hanger lug, 5 a crankshaft, 6 a crank arm fitted onto the crankshaft 5, and 7 its lock nut. Further, 8 (see FIG. 5) is a rear wheel, 9 is a rear wheel hub axle, 10 is a rear wheel sprocket, and 11 is a chain.

In this embodiment, a hollow disk-shaped carrier 12 (12a (see FIG. 3) is a lid plate that can be attached to and detached from the carrier body using screws, etc.) is fixed to the crankshaft 5 via the crank arm 6, and this carrier 12, a plurality of shafts 13 (six in this embodiment) are rotatably disposed at equal circumferential positions on the same circumference,
A disk-shaped planetary nucleus 14 is rotatably fitted to each of these shafts 13 at an eccentric position.

In this case, the thickness of the planetary core 14 is less than 1/2 of the length of the shaft 13 in the carrier 12, and
Adjacent planetary nuclei 14 are arranged alternately on the left and right in FIG. A ring-shaped planetary gear 16 is fitted onto the outer periphery of each of these planetary cores 14 via a one-way clutch 15 so that it can rotate only in one direction, and these planetary gears 16 are rotated in the axial direction of the crankshaft 5. Place it twice against.

That is, in this embodiment, three planetary gears 1
6 is disposed on the outer side of the carrier 12, and the remaining three planetary gears 16 are disposed on the inner side of the carrier 12 so as not to interfere with each other.

Although the one-way clutch 15 may be of any type, in this embodiment, as shown in FIGS. 1 and 2, a ratchet 15a is formed on the inner peripheral surface of a ring-shaped planetary gear 16, and A pawl 15b is provided on the outer periphery of the ratchet 14 to engage with the ratchet 15a to prevent rotation in only one direction, and is biased by a spring 15c so that the pawl 15b engages with the ratchet 15a.

Further, as shown in FIGS. 1 to 4, an inner eccentric cam 17 is rotatably fitted to the crankshaft 5 via a bearing 18, and this inner eccentric cam 1
An outer eccentric cam 19 is rotatably fitted on the outer periphery of the crank gear 7, and a sun gear 20 that meshes with each of the planetary gears 16 is formed integrally with the crank gear 21. It is rotatably fitted to the outer circumference of the eccentric cam 19. An arm 17a is provided protruding from one end of the inner eccentric cam 17, an arm 19a is provided protruding from one end of the outer eccentric cam 19, and the end of the outer wire 24 is connected to the end of the arm 19a via a stopper 23. At the same time, the end of the inner wire 25 is fixed to the end of the arm 17a via the stopper 26, and the inner wire 2 is fixed between the stoppers 23 and 26.
A coil spring 27 is inserted in 5. That is, in this way, by moving the inner wire 25 with respect to the outer wire 24, the inner eccentric cam 17 can be rotated with respect to the outer eccentric cam 19, thereby rotating the crankshaft of the sun gear 20. The amount of eccentricity with respect to 5 can be adjusted arbitrarily.

However, the eccentricity control device described above is merely an example in principle, and it goes without saying that other eccentricity control devices may be used in practice.

Further, a coil spring 28 is fitted to each shaft 13,
One end 28a of the spring 28 is locked to the planetary core 14 (the third
), and by locking the other end 28b of the spring 28 to the carrier 12, each planetary gear 1
A unidirectional rotational force is applied to the eccentric shaft 13 to the gear 6, so that each planetary gear 16 is always pressed into contact with the sun gear 20 and meshed with it.

Next, the operation of the apparatus of the present invention constructed as described above will be explained. In FIG. 2, l ₁ is the amount of eccentricity of the inner eccentric cam 17 with respect to the crankshaft 5, and l ₂ is the amount of eccentricity of the outer eccentric cam 19 with respect to the inner eccentric cam 17. Now, if l ₁ =l ₂ , then the eccentricity l of the sun gear 20 with respect to the crankshaft 5 in the state shown in FIG. 2 becomes l=l ₁ +l ₂ , which is the maximum eccentricity. From the state shown in FIG. 2, by relatively moving the outer wire 24 and the inner wire 25, the outer eccentric cam 19 is rotated 180 degrees with respect to the inner eccentric cam 17, resulting in the state shown in FIG. , the crankshaft 5 of the sun gear 20
The amount of eccentricity with respect to is 0. That is, by arbitrarily operating the inner wire 25 with respect to the outer wire 24, the amount of eccentricity of the sun gear 20 with respect to the crankshaft 5 is steplessly set to an arbitrary amount within the range shown in FIGS. 4 and 2. be able to.

Next, the operation of the continuously variable transmission mechanism will be explained. In the state shown in FIG. 4, the crankshaft 5 is
When rotates clockwise as shown by arrow A, the carrier 12 coupled to the crank arm 6 rotates together with the crankshaft 5, and as a result, each planetary nucleus 14 and planetary gear 16 also rotate together with the carrier 12 via the shaft 13. move. However, in this case, the amount of eccentricity of the sun gear 20 with respect to the crankshaft 5 is O, and each shaft 13 that pivots each planetary nucleus 14 at its eccentric position is in the same circle centered on the crankshaft 5 of the carrier 12. Since it is arranged on the circumference, sun gear 2
0 (the center of the crankshaft 5) O ₁ and the straight line connecting the center O ₂ of each planetary nucleus 14, the center O ₂ , and the axis 1
The intersecting angle θ with the straight line connecting the center O ₃ of 3 is the planetary nucleus 1
It remains unchanged in any phase of 4. Therefore, even if the carrier 12 rotates, each planetary nucleus 14 does not rotate at all with respect to the carrier 12.

However, since each planetary gear 16 meshes with the sun gear 20, each planetary gear 16 tries to rotate clockwise in FIG. 4 due to the load resistance of this sun gear 20, but this rotation is caused by the ratchet 15a. This is prevented by the action of a one-way clutch 15 consisting of a pawl 15b and a pawl 15b. Therefore, the sun gear 20 is rotated integrally with the crankshaft 5 in the same direction as indicated by arrow A in FIG. 4 by the planetary gear 16 which rotates integrally with the carrier 12. Therefore, the gear ratio in this case is 1:1.

Next, when the eccentric state shown in FIG. 2 is achieved by a speed change operation, as the crankshaft 5 rotates in the direction of arrow A, the carrier 12 rotates integrally with the shaft 5 as described above. As a result, each planetary core 14 also rotates together with the shaft 13, but in this case each planetary gear 1
Since the sun gear 20 with which gear 6 is meshed is eccentric with respect to the shaft 5, each planetary core 14 also rotates with respect to the carrier 12 from time to time.

That is, if the center of the sun gear 20 is O ₁ , the center of the planetary nucleus 14 is O ₂ , and the center of the shaft 13 is O ₃ , then θ, which is ∠O ₁ O ₂ O ₃ , is always constant in the case of Fig. 4. However, in the case of Fig. 2, θ ₁ , θ ₂ , and
It changes like θ ₃ , θ ₄ , θ ₅ , and θ ₆ . Then, a relationship of θ ₁ <θ ₂ <θ ₃ <θ ₄ >θ ₅ >θ ₆ >θ ₁ occurs between them.

That is, the planetary nucleus 14 between θ ₁ , θ ₂ , θ ₃ , and θ ₄ rotates in the direction of arrow B and also revolves around axis 5 in the direction of arrow A. Further, the planetary nucleus 14 between θ ₄ , θ ₅ , θ ₆ , and θ ₁ rotates in the direction of arrow C, and also revolves around axis 5 in the direction of arrow A. However, arrow C
The rotation of the planetary nucleus 14 in the direction is controlled by a one-way clutch 15
Since the rotation of the planetary core 14 in the direction of arrow B is not transmitted to the planetary gear 16 due to the action of the one-way clutch 15, the rotation of the planetary gear 16 at the highest speed in the direction of arrow C is eventually This is transmitted to the sun gear 20, and the sun gear 20 rotates at an increased speed in the direction of arrow A.

In this case, since there are six planetary gears 16 in this embodiment, the planetary gears 16 that are not in the rotation speed increasing region are not driven by the planetary nucleus 14, but are driven by the action of the one-way clutch 15 described above. planetary gear 1
Among 6 planetary gears 16, only one planetary gear 16 in the highest speed increasing range at that time drives the sun gear 20, and the remaining five planetary gears 16 are conversely rotated by the sun gear 20. become. That is, at this time, the ratchet 15a of the gear 16 rotates smoothly with respect to the pawl 15b.

The waveform curve D in Fig. 6 has the gear ratio on the ordinate,
The graph shows the speed change characteristics of the planetary core 14, with the rotation angle of the crankshaft 5 plotted on the abscissa. Baseline E in the figure indicates the rotational speed of the carrier 12 in the direction of arrow A, and the range of the waveform curve D below this baseline E is the deceleration range of the planetary core 14 (θ ₁ , θ ₂ , θ ₃ , θ ₄ The range of the waveform curve D above the base line E indicates the speed increase range of the planetary nucleus 14 (the range of θ ₄ , θ ₅ , θ ₆ , and θ ₁ ).

Further, FIG. 7 shows a speed-increasing drive state by six planetary gears 16, and its speed-increasing characteristics are shown by continuous curves D ₁ to _{D 6} . Note that the coordinates in FIG. 7 are the same as in FIG. 6.

As can be seen from this, in order to minimize variation in the speed ratio, it is preferable to use a large number of planetary gears 16. Since six planetary gears 16 are used in this embodiment, the drive range of each planetary gear 16 with respect to the sun gear 20 is approximately 60 degrees. Therefore, as seen from FIG. 7, in this embodiment, a rotational driving force with almost no pulsation can be obtained even during speed increase.

In addition, in the transition portion of each drive range from D ₁ to _{D 6} in FIG. 7, each planetary gear 16 and sun gear 2
If there is a backlash at the meshing point with 0, vibration will occur in the transmission system due to the backlash when the planetary gear 16 changes from the driven state to the driving state.
is always pressed against the sun gear 20 by the action of the coil spring 28, so there is no backlash, so the above-mentioned vibration does not occur.

In addition, in the above explanation, the case of the speed increasing ratio O and the case of the maximum speed increasing ratio have been explained, but the eccentric operation amount by the outer wire 24 and the inner wire 25 described above can be changed to an arbitrary value between FIGS. 4 and 2. It is obvious that the device of the present invention can steplessly obtain any speed ratio by setting the speed ratio to a certain value.

(Effects of the Invention) Next, the effects of the device of the present invention will be explained. Since the continuously variable transmission of the present invention is installed on the crankshaft of the bicycle instead of the rear wheel hubshaft as described above,
Not only can the diameter ratio between the crank gear and the rear wheel sprocket be increased, but the overall size of the transmission device can also be prevented from becoming large.

In addition, this type of continuously variable transmission transmits power by meshing each planetary gear with the sun gear, so if there is a bump at the meshing point between each planetary gear and the sun gear, this will cause the drive during speed-up transmission. This was a cause of vibration in the transmission system when the planetary gears were shifted, but in the present invention, each planetary gear is always brought into elastic pressure contact with the sun gear by the action of a spring. There is no bumpiness at the meshing portion between the gear and each planetary gear. Therefore, the device of the present invention has the effect that there is no possibility of the above-mentioned vibration occurring in the transmission system.

[Brief explanation of drawings]

Fig. 1 is an exploded perspective view of the device of the present invention, Fig. 2 is a front view showing a part of the device of the present invention in a cutaway state, Fig. 3 is a vertical side view of Fig. 2, and Fig. 4 is a side view of Fig. 2. Eccentricity O
5 is a side view of the bicycle equipped with the device of the present invention, FIG. 6 is a diagram of the speed change characteristics of the device of the present invention using the planetary core, and FIG. FIG. 3 is a speed increase characteristic diagram showing a speed increase state. 5...Crankshaft, 6...Crank arm, 1
2...Carrier, 13...Axis, 14...Planetary nucleus,
15... One-way clutch, 16... Planetary gear, 1
7...Inner eccentric cam, 19...Outer eccentric cam, 2
0...Sun gear, 21...Crank gear, 24...
...Outer wire, 25...Inner wire, 2
8...Coil spring.

Claims (1)

[Claims] 1. A carrier is fixed to the crankshaft of a bicycle, a plurality of shafts are arranged on the same circumference of this carrier, a planetary nucleus is rotatably fitted to each of these shafts at an eccentric position, and each of these planetary nuclei A planetary gear is fitted to the crankshaft so that it can rotate in only one direction via a one-way clutch, and a sun gear integral with the crank gear is provided on the crankshaft so as to be eccentric and rotatable with respect to the crankshaft, and each of the planetary gears A continuously variable transmission for a bicycle, characterized in that the gear is always biased so as to be in pressure contact with the sun gear.