JPS5922102B2 - 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 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;
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 extending over 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 Che 7 is fine.

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 enters into this gap 7 from the outside or rainwater enters, the teeth may be damaged. However, there was a problem 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 closing up the disc 8, but this method has disadvantages such as a reduction in the dust-proofing 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 internal floating wheel, and external teeth that rotate while being sandwiched between the guide plates. An annular seal ring is provided on both sides of the gear that slides against the side of the guide plate, and by isolating the gap of the internal gear set that meshes in a floating state from the outside, it prevents foreign objects and rainwater from entering the meshing part. In addition to protecting the lubricants such as grease applied to the meshing parts for a long period of time and minimizing wear on the tooth surfaces, it also prevents damage to the teeth due to biting foreign objects, as well as contact friction resistance for dust prevention. The purpose of this invention is to stabilize the meshing of the internal gear set and improve single-drive efficiency by reducing this as much as possible.

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 external gear 2 is made slightly smaller than the width of the internal floating wheel 3, and hollow disk-shaped guide plates 8 are applied to both sides of the internal floating wheel 30. The guide plate 8 is fixed to the internal floating wheel 3 by bolts 9 and nuts 10 passing through the internal floating wheel 3.

The outer diameter of the guide plate 8 is slightly larger than the outer diameter of the toothed belt 6 wrapped around the internal floating wheel 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.

Next, an annular groove 2b is provided on both sides of the external gear 20 at a position slightly smaller in diameter than the root diameter, and a ring 12 made of an elastic material such as rubber, Teflon, or nylon is fitted into this groove 2b. A part of this seal ring 12 is made to protrude from the side surface of the external gear 2 so as to come into sliding contact with the inner surface of the guide plate 8.

Next, the effects of the dustproof device of the present invention constructed as described above 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, since the internal floating wheel 3 does not have a shaft, the rotation center of the internal floating wheel 3 is eccentric to the rotation center of the external gear 2.

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 way as the internal floating wheel 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, the seal rings 12 fitted on both sides of the external gear 20
protrudes outward from the side surface of the external gear 2, and only this seal ring 12 comes into sliding contact with the inner surface of the guide plate 8, so that the inner m3a of the external gear 2 and the internal floating wheel 3 is fitted into this. It is possible to completely block the gap 7 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 external gear 2 fitted with this seal ring 12, and slight irregularities on the surface may cause problems. Since this does not occur, it is also possible to reduce the amount of finishing work required for the side wall portions.

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 disk-shaped guide plates are attached to both sides of the internal floating wheel, and side surfaces of the guide plate are attached to both sides of the external gear that is rotated 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 into contact with the floating internal gear set.