JPS5922104B2 - Dust prevention device for floating internal gear set - Google Patents

Description

Detailed Description of the Invention The present invention relates to a ring-shaped internal floating wheel having an internal gear in a transmission device having an automatic tension adjustment function of a transmission band such as a belt or a chain. This invention relates to a dustproof device for a floating internal gear set consisting of gears.

FIGS. 1 and 2 show an example of a transmission device having an automatic tension adjustment function of a transmission band, which is applied to a bicycle drive device.

In the figure, 1 is a drive shaft, 2 is an external gear fixed to the drive shaft 1, and 3 is a ring-shaped internal floating wheel with internal teeth 3a on the inner periphery. They interlock.

4 is a driven shaft held at a position separated from the drive shaft 1;
5 is a driven wheel which is the other transmission wheel provided on the driven shaft 4 of the cigarette; 6 is a transmission band extending over the outer circumference of the internal floating wheel 3 and the outer circumference of the driven wheel 5; this transmission band is a belt. Or cheno.

In this embodiment, a toothed belt (timing belt) is used.

When tension as shown by arrow B in FIG. 1 acts on the transmission band 6 of this transmission device, if the transmission band 6 is loose, the internal floating wheel 3 moves eccentrically downward, causing the transmission band 6 to Automatically absorbs slack.

This function is the automatic tension adjustment function of the transmission band.

However, when a transmission mechanism having an internal floating wheel as described above is assembled into a vehicle such as a bicycle, the internal floating wheel of the internal gear set meshing with the external gear 2 in a floating state as described above. 3
Since there is a gap 1 between the internal teeth 3a of the external gear 2 and the external teeth 2a of the external gear 2, if dust or other foreign matter or rainwater enters the gap 7 from the outside, the teeth will be damaged. There were also problems in that tooth wear increased.

In order to solve this problem, for example, as shown in FIG. 3, hollow discs 8 are applied to both sides of the internal floating wheel 30 and fixed with bolts 9 and nuts 10, so that these discs 8 are connected to the external gear. The gap 7 is in sliding contact with the side surface of 2.
There is also a method of blocking the disc 8, but this method has drawbacks such as a reduction in the dustproof effect and an increase in sliding contact resistance if the disc 8 is even slightly deformed or bent.

The present invention has been made to solve these problems, and includes hollow disc-shaped guide plates attached to both sides of the internally floating vehicle, and an annular guide plate attached to the inner circumference of the guide plate. By fitting a seal ring and sliding the inner end of this seal ring against the side surface of the external gear, the gap of the internal gear set that meshes in a floating state is isolated from the outside, thereby preventing foreign matter from entering the meshing part. It prevents the intrusion of water and rainwater, protects lubricants such as grease applied to the meshing parts for a long period of time, and minimizes wear on the tooth surfaces.In addition, it prevents tooth damage caused by biting foreign objects, and has a dustproof dam. The purpose of this invention is to stabilize the meshing of the internal gear set and improve driving efficiency by minimizing the contact friction resistance of the internal gear set.

The present invention will be explained in detail below based on FIG.

In the drawings, the same reference numerals as those described above indicate equivalent parts.

Note that 11 is a crank arm integrally connected to the drive shaft 1.

In the present invention, the width of the external gear 2 is made slightly smaller than the width of the internal floating bundle 3, hollow disc-shaped guide plates 8 are applied to both sides of the internal floating bundle 3, and these guide plates 8 The guide plate 8 is fixed to the internal floating bundle 3 by bolts 9 and nuts 10 passing through the internal floating bundle 3.

The outer diameter of the guide plate 8 is made slightly larger than the outer diameter of the toothed belt 6 wound around the internal floating bundle 3, and the inner diameter of the guide plate 8 does not interfere with the drive shaft 1 integrated with the external gear 2. It is desirable that the range be as small as possible.

Further, an annular seal ring 12 having a substantially L-shaped cross section as shown in FIG. 4 is formed using an elastic material such as rubber, Teflon, or nylon. The inner end 12a of the seal ring 12 is brought into sliding contact with the side surface of the external gear 2.

In the embodiment shown in FIG. 4, a V-shaped groove having an inner end 12aKi is formed, and the lip portions on both sides thereof are brought into contact with the side surfaces of the external gear 2.

In this case, the flange portion 12b of the seal ring 12 may be bonded to the guide plate 8 using an adhesive or the like.

Next, the operation of the dust-proofing device of the present invention, which is constructed like water supply, will be explained.

When the pedal (not shown) at the end of the crank arm 11 that is integrated with the external gear 2 is depressed, the external gear 2 rotates, and the internal floating bundle 3 that meshes with the external gear 2 in a floating state rotates in the same direction. The first driven wheel 5 further rotates via the transmission band 6.

In this case, since the inscribed floating vehicle 3 does not have an axis, the inscribed floating vehicle 3
The 0 rotation center is eccentric with respect to the 20 rotation center of the external gear.

For this reason, the hollow disk-shaped guide plates 8 provided on both sides of the internal floating wheel 30 also move in the same manner as the internal floating bundle 3, so in the one in FIG. It slides on the side of gear 2.

If the inner surface of the guide plate 8 directly slides on the side surface of the external gear 2 in this way, there will be a lot of sliding friction and a gap will be created on the sliding surface, making the dustproof effect incomplete. However, the present invention shown in FIG. In the device, only the inner end portions 12a of the seal rings 12 fitted to the inner peripheral portions of the guide plates 8 on both sides of the external gear 2 are connected to the external gear 2.
This makes it possible to completely block the gap 7 between the external gear 2 and the internal teeth 3a of the internal floating bundle 3 from the outside.

Further, by appropriately selecting the material of the seal ring 12 in order to reduce the sliding contact resistance, the sliding frictional resistance can be further reduced to a very small value.

Further, as in the present invention, the side surface of the external gear 2 and the seal ring 1
If only 2 are in contact with each other, there is no need for precision machining of the side walls of the inscribed floating bundle 3 and the guide plate 8, and slight unevenness on the surface does not become an obstacle, resulting in the effect that finishing machining of the side walls can be reduced. It will be done.

Although the present embodiment has been described with respect to the case where the floating internal gear set is used as the driving side, it goes without saying that the present invention is also applicable to the case where the floating internal gear set is used as the driven side.

[Brief explanation of the drawing]

1 is a front view of a belt transmission with a floating internal gear set; 2. FIG. The drawings are a cross-sectional view taken along the line A-A in FIG. 1, FIG. 3 is a cross-sectional view showing a state in which a conventional dust-proofing mechanism is provided in the transmission station, and FIG. 4 is a cross-sectional view showing the dust-proofing device of the present invention. 1... Drive shaft, 2... External gear, 3.
...inscribed floating bundle, 3a...internal tooth, 4...
...Driven shaft, 5...Driven wheel (transmission wheel), 6
......Transmission band (toothed belt), 7...
Gap, 8... Guide plate, 9... Bolt,
10...Nut, 11...Crank arm, 12...Seal ring, 12a...
...Inner end, 12b...Brim part.

Claims (1)

[Claims] 1. A transmission device in which a ring-shaped internal floating wheel with internal teeth on the inner periphery is meshed with an externally toothed gear, and a transmission band is stretched between a transmission wheel installed at a separate position and the outer periphery of the internal floating wheel. In the floating internal gear set, hollow disc-shaped guide plates are attached to both sides of the internal floating gear, and an annular seal ring is fitted to the inner circumference of the guide plate, and this seal A dustproof device for a floating internal gear set, characterized in that the inner end of the ring is in sliding contact with the side surface of the external gear.