JPS6241445A - Planetary gear - Google Patents

Abstract

PURPOSE:To enhance the reliability and durability of a planetary gear, by coupling a sun gear with an input shaft through the intermediary of a flexible cylindrical member in order to make the sun gear self-align with the input shaft so that the sun gear may transmit torque uniformly to planetary gears. CONSTITUTION:An input shaft 8 is coupled to the front end of a flexible cylindrical member 16 which is formed at its rear end with a sun gear 20. With this arrangement, the sun gear 20 may yield and twist relative to planetary gears 22 to self-align with the input shaft to transmit uniform torque to the planetary gears.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a planetary gear train with a device for equalizing the transmitted loads between a sun gear and a plurality of planet gears.

・Prior art Most conventional planetary gear devices have a structure in which a sun gear and a carrier that pivotally supports the planetary gear rotate concentrically with each other while maintaining a rigid relationship within the internal gear. This structure has a problem in that the load is not evenly distributed between the sun gear and each planetary gear due to machining accuracy, resulting in noise. As a solution to this problem, various structures that support the sun gear shaft and internal gear in a flexible state are disclosed in Japanese Patent Publication No. 38-9158, Japanese Utility Model Publication No. 40-22814, and Japanese Patent Publication No. 43-2.
This method is disclosed in Japanese Utility Model Publication No. 4616, Japanese Utility Model Application Publication No. 50-26286, Japanese Patent Publication No. 15987-1987, and the like. However, all of these solutions have the disadvantage that they not only have a complicated structure and a long shaft length, but also cannot form a compact two-stage reduction gear in which a planetary gear device is connected in series.

Problems to be Solved by the Invention It is an object of the present invention to provide a planetary gear device that eliminates the above-mentioned drawbacks of the prior art without requiring high machining accuracy.

Means for Solving the Problems The specified invention includes: a flexible tubular body that is fixed to the front end of an input shaft and whose rear part covers the input shaft with play; a sun gear formed at the rear end of the tubular body; It is characterized by having a plurality of planetary gears that are pivotally supported by a carrier that is transmission-coupled with the output shaft and rotates concentrically with respect to the input shaft, and that mesh with the sun gear and the internal gear.

The second invention also provides a flexible tubular body that is fixed to the front end of the input shaft and whose rear part covers the input shaft with play; a first sun gear formed at the rear end of the tubular body; A plurality of first carriers are pivotally supported by a first carrier rotatably disposed with a small gap outside the body and mesh with the first sun gear and the internal gear.
A planetary gear, a second sun gear formed on the front part of the first carrier, and a second sun gear and an internal gear that are pivotally supported by the second carrier that is transmission-coupled with the output shaft and rotates concentrically with respect to the input shaft. It is characterized by having a plurality of second planetary gears that mesh with each other.

In the specific invention, since the sun gear is formed at the rear end of the flexible tubular body and can be bent and twisted relative to the input shaft, the sun gear is automatically adjusted so that the transmitted torque is uniform with respect to the planetary gear. to adjust oneself.

Further, in the second invention, since the first sun gear performs the same self-aligning action as described above and the first carrier has a small gap with the flexible tubular body, the second sun gear Since the first carrier and the first sun gear have an integral structure that is short in the axial direction, even a two-stage reduction gear can be self-aligned so that the transmitted torque to the second planetary gear is uniform. Dimensions become significantly smaller.

Example 1 and 2 show an embodiment having a two-stage reduction mechanism.

An output shaft 5 is supported by bearings 3 and 4 on an output side case 2 having a mounting leg 1, and an input side case 7 is fixed to the case 2 via an internal gear 6 concentric with the output shaft 5. The input shaft 8 is supported on the case 7 by a bearing 9 concentrically with the output shaft 5,
The tip 1111 diameter portion 10 of the input shaft 8 is supported by a bearing 12 in a center hole 11 formed at the inner end of the output shaft.

The input shaft 8 has a medium diameter portion 14 and a small diameter portion 15, the diameter of which decreases stepwise inward from a flange 13 that contacts the inside of the case 7. The flexible tubular body 16 concentrically covers the medium diameter portion 14 with a clearance 17, and its front end covers the small diameter portion 15.
It is fixed to the input shaft 8 by the pin 18. The flexible tubular body 16 also has a gap with the output shaft center hole 11, has a wall thickness and an axial length that can be elastically bent and twisted with respect to the input shaft 8, and has a rear A first sun gear 20 is formed at the end.

The first carrier 21 has a boss portion that has a center hole that is approximately the same diameter as the center hole 11, and is loosely engaged with the flexible tubular body 16, and a rear end that is in contact with the first sun gear 20. A second sun gear 25 is formed at the front end of the boss portion, and the front surface of the second sun gear 25 is formed at the inner end of the output shaft 5. The axial position is regulated in contact with the rear surface of 26. Three second planetary gears 27 arranged at equal intervals on the circumference are supported on the second carrier 26 by pins 28 and bearings 29, and the first. Second planetary gear 22.
27 are meshed with the internal gear 6, and the first. Second
It meshes with the sun gear 20.25.

With the above structure, the rotation of the input shaft 8 is controlled by the first sun gear 20, the first planetary gear 22, and the internal gear 6.
The first carrier 21 is rotated at a reduced speed by the stage planetary gear system, and this rotation is further decelerated by the second stage planetary gear system constituted by the second sun gear 25, second planet gear 27, and internal gear 6, and output. The signal is transmitted to the shaft 5.

In the first stage planetary gear device, the front end of the flexible tubular body 16 is fixed to the input shaft, and the rear end can be bent and twisted in the diametrical direction with respect to the input shaft 8. If there is any discrepancy in the transmitted rotational moments between the two planetary gears 22, the first sun gear 20 is elastically displaced by the resultant force of the discrepancy, thereby eliminating the discrepancy.

In the second stage planetary gear device, if there is a difference in the transmitted rotational moment between the second sun gear 25 and the second planetary gear 27 as described above, the first carrier 21 is connected to the boss portion and the flexible tubular body 16. Since it rotates in a floating state with a gap between the two, it is displaced by the resultant force due to the above discrepancy, thereby eliminating the discrepancy.

Even if the flexible tubular body 1G has a sufficient length to perform a self-aligning action, it is fixed to the front end of the input shaft and extends rearward, and the front end of the input shaft is housed in the center hole of the output shaft. Furthermore, since the axial length of the first carrier having the second sun gear is small, the first stage planetary gear set and the second stage planetary gear set are arranged in series in a compact manner.

If the second stage planetary gear device is omitted, the first carrier 2
1 may be directly formed at the rear end of the output shaft 5.

Effects of the Invention The present invention has the above configuration, and the structure for evenly distributing the load to the idler gear is extremely simple, reliable, and durable, and does not require high precision or processing technology, making it inexpensive. This has the advantage that it can be manufactured in a compact manner, and the speed reduction device having the first stage and second stage planetary gear devices can also be manufactured compactly.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of one embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of a flexible tubular body. 5... Output shaft 6... Internal gear 8... Input shaft 16... Flexible tubular body 20... Sun gear,
First sun gear 21...carrier, first carrier 22...planetary gear, first planetary gear 25...second sun gear 26...second carrier 27...second planetary gear

Claims (2)

[Claims] (1) A flexible tubular body that is fixed to the front end of the input shaft and whose rear part covers the input shaft with play; a sun gear formed at the rear end of the tubular body; and a sun gear that is transmission-coupled with the output shaft and attached to the input shaft. A planetary gear device having a plurality of planetary gears that are pivotally supported by a carrier that rotates concentrically and mesh with a sun gear and an internal gear. (2) A flexible tubular body that is fixed to the front end of the input shaft and whose rear part covers the input shaft with a play, a first sun gear formed at the rear end of the tubular body, and a small gap on the outside of the flexible tubular body. a plurality of first planetary gears that are pivotally supported by a first carrier rotatably disposed with a plurality of planetary gears in mesh with the first sun gear and the internal gear; and a second planetary gear formed at the front of the first carrier. a sun gear; and a plurality of second carriers that are pivotally supported by a second carrier that is transmission-coupled with the output shaft and rotates concentrically with respect to the input shaft, and that mesh with the second sun gear and the internal gear.
A planetary gear device having a planetary gear.