JPS5922103B2 - 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, and an external floating wheel meshing with the internal floating wheel. 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 7 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, which is in a floating state with the external gear 2. They are internally interlocked.

4 is a driven shaft held at a position separated from the drive shaft 1;
Reference numeral 5 denotes a driven wheel which is the other transmission wheel provided on this driven shaft 4, and 6 denotes a transmission band that extends around the outer periphery of the internal floating wheel 3 and the outer periphery of the driven wheel 5, and 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 7 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. 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 an external gear, and an internal gear that rotates while being sandwiched between the guide plates. Annular seal rings are provided on both sides of the floating wheel that slide against the sides of the guide plate, and the gap between the internal gear set that meshes in the floating state is isolated from the outside, thereby preventing foreign matter and rainwater from entering the meshing part. In addition to protecting the grease and other lubricants applied to the meshing parts for a long period of time and minimizing wear on the tooth surfaces, the contact friction resistance of the dust-proof reservoir prevents tooth damage caused by biting foreign objects. The purpose is to make the internal gear set as small as possible, thereby stabilizing the meshing of the internal gear set and improving drive efficiency.

The present invention will be described in detail with reference to FIG. 4 below.

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 internal floating wheel 3 is made slightly smaller than the width of the external gear 2, and hollow disc-shaped guide plates 8 are applied to both sides of the external gear 20. The guide plate 8 is fixed to the external gear 2 by bolts 9 and nuts 10 passing through the gear 2.

The outer diameter of the guide plate 8 is such that it slightly protrudes outward in the meshing direction between the external gear 2 and the internal floating wheel 3 than the outer diameter of the toothed belt 6 wrapped around the internal floating wheel 3, and It is desirable that the inner diameter of the plate 8 is smaller than the root diameter of the external gear 2 to some extent.

Next, an annular groove 3 is formed on both sides of the internal floating wheel 30 at a position slightly larger than the bottom diameter of the internal gear of the internal floating wheel 3.
A seal ring 12 made of an elastic material such as rubber, Teflon, or nylon is fitted into the groove 3b, and a part of the seal ring 12 is made to protrude from the side surface of the internal floating wheel 3.
It is made to come into sliding contact with the inner surface of the guide plate 8.

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 wheel 3 that meshes with the external gear 2 in a floating state rotates in the same direction. The driven wheel 5 further rotates via the transmission band 6.

In this case, the inscribed floating wheel 3 has no axis, so the inscribed floating rate is 3
The 0 rotation center is eccentric with respect to the 20 rotation center of the external gear.

Therefore, in the one shown in FIG. 3, the inner surface of the guide plate 8 near the center always slides on the side surface of the external 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, a seal ring 1 fitted on both sides of an internal floating wheel 30
2 protrudes outward from the side surface of the internal floating wheel 3, and only this seal ring 12 makes sliding contact with the inner surface of the guide plate 8. Internal teeth 3
It is possible to completely shut off the gap 7 with a 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.

Furthermore, if only the seal ring 12 is brought into contact with the guide plate 8 as in the present invention, there is no need for precision machining of the side wall of the internal floating wheel 3 fitted with this seal ring 12, and the surface may be slightly uneven. 1df14 It is also possible to obtain young fruit that does not cause any harm, so that the finishing work on the side wall can be reduced.

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]

Fig. 1 is a front view of a belt transmission device having a floating internal gear set, Fig. 2 is a sectional view taken along line AA in Fig. 1, and Fig. 3 shows the transmission device equipped with a conventional dust-proof mechanism. Cross section, 4th
The figure is a sectional view showing the dustproof device of the present invention. 1... Drive shaft, 2... External gear, 3.
...Internal floating wheel, 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.

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 external gear, and guide plates are attached to both sides of the internal floating wheel that rotates while being sandwiched between the guide plates. A dustproof device for a floating internal gear assembly, characterized by having an annular seal ring that slides on the side surface.