JP2542196B2 - Bicycle belt drive - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present disclosure relates to a belt driven bicycle, and more particularly to a bicycle belt driving device having an automatic tension adjusting function.

(Technical Background of the Invention and Problems Thereof) FIG. 3 shows a conventional bicycle belt drive device. That is, this belt drive device is provided with a large-diameter drive pulley 2 attached to the crankshaft 1 and a small-diameter driven pulley 3 attached to a rear wheel side shaft (not shown). A toothed belt 4 is wound around the belt. In the belt drive device having such a structure, in order to prevent the toothed belt 4 from coming off or slipping during traveling of the bicycle, the idlers 5a approaching each other,
The toothed belt 4 is pressed by 5a to give a constant tension to the toothed belt 4. But like this the idler 5a,
When the toothed belt 4 is pressed by 5a, the toothed belt 4 is rotationally driven while being bent at the idler 5a position, so that the toothed belt 4 is seriously damaged, and therefore, the toothed belt 4 needs to be replaced in a short period of time.

FIG. 4 discloses another conventional belt driving device. In the conventional belt drive device as shown in FIG. 4, a drive gear 6 that is integrally rotated with the crankshaft 1,
Between the toothed belt 4 and the toothed belt 4, there is provided a floating gear 7 that eccentrically moves around the drive gear 6. According to this belt drive device, when tension is applied to the toothed belt 4 via the floating gear 7 that meshes with the drive gear 6 with the internal teeth 7a, the toothed belt 4
Since the floating gear 7 eccentrically moves around the drive gear 6 when there is a slack in the toothed belt 4, the idler that presses the toothed belt 4 is not used, and thus the durability of the toothed belt 4 is not impaired. It is possible to prevent the toothed belt 4 from loosening.

However, in the belt drive device provided with the floating gear 7 and having the automatic tension adjusting function, the rotation of the crankshaft 1 is decelerated by the meshing with the floating gear 7 that meshes with the drive gear 6, and thus this decelerated rotation is compensated. Therefore, it is necessary to set the outer diameter of the floating gear 7 to be large, which leads to an increase in the size of the belt drive device.

(Object of the Invention) An object of the present invention is to reduce the size of a belt driving device having an automatic tension adjusting function.

(Summary of the Invention) The invention of the present application is directed to an outer gear part around which a toothed belt for transmitting a rotational force to the rear wheel is wound, and an inner gear provided on an inner part of the outer gear part and having outer teeth on an outer peripheral surface. A floating gear that is fixed to the crankshaft, and that when the belt is loosened, the outer gear portion and the inner gear portion are allowed to allow eccentric movement of the floating gear to automatically absorb the looseness. And a crank gear having inner teeth meshing with the inner gear portion provided on an inner peripheral surface thereof, the rotation of the crank gear causes the floating gear to rotate and the floating gear to loosen the belt. It is characterized in that the eccentric movement is performed accordingly.

In the bicycle belt drive device according to the present invention, the rotation of the crankshaft is transmitted to the toothed belt via the floating gear that meshes with the crank gear. The crank gear and the floating gear are meshed with each other by meshing the outer teeth of the inner gear portion provided in the eccentrically movable floating gear with the inner teeth of the crank gear.

Therefore, when the rotation of the crank gear is accelerated and transmitted to the floating gear, the rotational driving force is transmitted to the toothed belt wound around the outer gear portion. At this time, if the toothed belt is loose, the floating gear eccentrically moves around the inner teeth of the crank gear with which the outer teeth of the inner gear portion mesh. That is, the floating gear rotates so that its center position is displaced by rotation. The eccentric movement of the floating gear absorbs the looseness of the toothed belt and maintains a constant tension on the toothed belt.

In addition, the meshing of the internal teeth of the crank gear with the external teeth of the floating gear causes the floating gear to rotate at an increased speed. It is possible to secure a predetermined speed increasing ratio without setting a large value, and by reducing the diameter of the floating gear, it is possible to reduce the size of the belt drive device having the automatic tension adjusting function.

Embodiments of the Invention Embodiments of the present invention will be described in detail below with reference to the drawings.

The bicycle belt drive device according to the present invention includes a crank gear 10, as shown in FIGS. 1 and 2. This crank gear 10 is provided with teeth 10a on its inner peripheral surface and side walls 10b.
Are integrally formed. Square hole 10c at the center of side wall 10b
Is provided, and a square fitting portion 11a protruding from one end of the crank arm 11 is inserted into the square hole 10c. The fitting portion 11a is fitted on the square crankshaft 12, and the cap 13 is screwed onto the threaded portion 12a at the tip of the crankshaft 12. A pedal (not shown) is attached to the other end of the crank arm 11.

The floating gear 14 driven by the crank gear 10 has an outer gear portion 14A having a large diameter. The outer gear portion 14A has teeth 14a provided on the outer peripheral surface thereof, and a toothed belt 15 is wound around the outer gear portion 14A. Inside the outer gear 14A, the inner gear 1 is coaxial
4B is formed. The inner gear portion 14B has a diameter slightly smaller than that of the crank gear 10, and has teeth 14b on the outer peripheral surface. A cover member 16A is integrally formed on one end surface of the outer gear portion 14A and the inner gear portion 14B, and the crank arm 1 is formed on the other end surface of the outer gear portion 14A.
Another cover member 16B arranged between 1 and the crank gear 10
Is bolted. The crank gear 10 is located between the outer gear portion 14A and the inner gear portion 14B and its teeth 10
The a meshes with the teeth 14b of the inner gear portion 14B.

The toothed belt 15 is made of a rubber material containing Kepler fibers, and is wound around the outer gear portion 14A and the driven pulley 17.

In the belt drive device having the above configuration, when the crank arm 11 is rotated by pedal operation, the crank gear 10 is rotated accordingly, so that the floating gear 14 is eccentric through the meshed inner gear portion 14B. It moves and a predetermined tension is applied to the toothed belt 15. Therefore, thereafter, the inner gear portion 14B is rotated by the crank gear 10, so that the toothed belt 15 is rotationally driven by the outer gear portion 14A.

In this way, when tension is applied to the toothed belt 15 by the eccentric movement of the floating gear, the toothed belt 15 can be driven to rotate without being bent, and thus the toothed belt 15 is not damaged even if it is used for a long period of time. There is nothing to do.

In addition, the crank gear 10 allows the inner gear part 14 to have a slightly smaller diameter.
Since B is rotated, the rotation speed of the outer gear portion 14A increases,
Therefore, the driven pulley 17 can be rotated at a predetermined speed without increasing the outer diameter of the outer gear portion 14A. Therefore, by reducing the diameter of the floating gear 14, the belt driving device can be downsized.

(Effect of the Invention) According to the present invention, an outer gear part around which a floating gear is wound around a toothed belt and an inner gear part having teeth on its outer peripheral surface are formed, and the inner peripheral part is attached to a crankshaft. By engaging the inner gear part with the crank gear that has teeth on the surface, it is possible to rotate the toothed belt without bending it by eccentrically moving the floating gear, and to rear without increasing the size of the floating gear. The rotation speed on the wheel side can be secured, and the diameter of the floating gear can be reduced, whereby the belt drive device having the automatic tension adjusting function can be downsized.

[Brief description of drawings]

1 and 2 are an exploded perspective view and a front view of a belt driving device according to the present invention, and FIGS. 3 and 4 are front views showing a conventional belt driving device, respectively. 10 …… Crank gear, 10a …… Tooth, 11 …… Crank arm, 12 …… Crank shaft, 14 …… Floating gear, 14A …… Outer gear, 14B …… Inner gear, 15 …… Toothed belt.

Claims (1)

(57) [Claims] 1. A floating system comprising an outer gear part around which a toothed belt for transmitting a rotational force is wound to a rear wheel side, and an inner gear part provided on an inner part of the outer gear part and having outer teeth on an outer peripheral surface thereof. A gear and a gear fixed to the crankshaft and disposed between the outer gear portion and the inner gear portion to allow eccentric movement of the floating gear to automatically absorb the looseness of the belt when the belt loosens. A crank gear having inner teeth meshing with the inner gear portion on the inner peripheral surface thereof, the floating gear is rotated by the rotation of the crank gear, and the floating gear is eccentrically moved according to the looseness of the belt. A belt drive device for a bicycle, characterized in that