JP2023100278A - Planetary gear device - Google Patents

Abstract

To modify a tooth trace of a sun gear part while suppressing deterioration of meshing of a male spline part.SOLUTION: A planetary gear device 1 comprises a sun gear shaft 41 having a sun gear part 43, and a planetary gear 44 meshing with the sun gear part 43. The sun gear shaft 41 has a male spline part 42 for coupling with a front stage shaft, and each tooth part of the sun gear part 43 extends in an axial direction to form the male spline part 42. The sun gear part 43 has a crowning part 43b whose tooth thickness gradually decreases toward both end parts in the axial direction. The male spline part 42 has a change in the tooth thickness in the axial direction smaller than a tooth thickness change amount of the crowning part 43b.SELECTED DRAWING: Figure 3

Description

The present invention relates to a planetary gear system.

In a planetary gear device, a sun gear portion that meshes with the planetary gears and a male spline portion that is connected to the front stage shaft are formed on the same sun gear shaft (see, for example, Patent Document 1). In such a planetary gear device, the sun gear shaft may be subjected to tooth lead modification to improve meshing of the sun gear portion.

JP 2014-159814 A

However, if the tooth trace of the sun gear shaft is simply modified, the male spline portion may be machined as an extension of the sun gear portion, and the meshing of the male spline portion may deteriorate.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to modify the tooth trace while suppressing the deterioration of the engagement of the male spline portion.

The present invention provides a planetary gear device comprising a sun gear shaft having a sun gear portion and planetary gears meshing with the sun gear portion,
The sun gear shaft has a male spline portion for coupling with the front stage shaft, and the male spline portion is formed by extending each tooth portion of the sun gear portion in the axial direction,
The sun gear portion has a crowning portion whose tooth thickness gradually decreases toward both ends in the axial direction,
The male spline portion has a smaller change in tooth thickness in the axial direction than the crowning portion.

The present invention also provides a planetary gear device comprising a sun gear shaft having a sun gear portion, a planetary gear meshing with the sun gear portion, and a pre-stage shaft connected to the sun gear shaft,
The sun gear shaft has a male spline portion connected to the front stage shaft, and the male spline portion is configured by extending each tooth portion of the sun gear portion in the axial direction,
The sun gear portion has a crowning portion whose tooth thickness gradually decreases toward both ends in the axial direction,
The male spline portion has a tooth thickness that changes in the axial direction continuously from the crowning portion,
In the front shaft, a female spline portion that meshes with the male spline portion has a tooth thickness that changes in the axial direction in accordance with a change in tooth thickness in the axial direction of the male spline portion.

According to the present invention, it is possible to modify the tooth trace of the sun gear portion while suppressing deterioration of meshing of the male spline portion.

It is a sectional view showing a planetary gear device concerning an embodiment. FIG. 2 is an enlarged view of a main portion of FIG. 1; (a) is a view of the teeth of the input shaft of the second planetary gear mechanism viewed from the axial direction, and (b) is a cross-sectional view of the teeth along line III-III in (a). (a) is a cross-sectional view showing a modification of the teeth of the input shaft of the second planetary gear mechanism, and (b) is a view of the teeth of the input shaft of the second planetary gear mechanism and tooth grooves of the female spline portion meshing therewith. FIG. 11 is a cross-sectional view showing another modified example;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Overall Configuration of Planetary Gear Device]
FIG. 1 is a cross-sectional view showing a planetary gear device 1 according to this embodiment.
As shown in this figure, the planetary gear device 1 includes a worm speed reduction mechanism 20 and at least two stages of simple planetary gear mechanisms (a first planetary gear mechanism 30 and a second planetary gear mechanism 40). They are provided in this order on the power transmission path.
In the following description, the direction along the central axis Ax of the planetary gear device 1 will be referred to as the "axial direction," the direction perpendicular to the central axis Ax as the "radial direction," and the direction of rotation about the central axis Ax as the "circumferential direction.""Direction". Further, in the axial direction, the side to which the motor is connected (the upper side in the drawing) is called the "input side", and the side to which the driven member is connected (the lower side in the drawing) is called the "output side".

A motor (not shown) is connected to the worm reduction mechanism 20 . A rotating shaft of the motor is connected to a worm pinion 21 of a worm speed reduction mechanism 20 via a coupling. The worm pinion 21 meshes with the worm gear 22 to change the power transmission direction to a substantially right angle. A worm gear 22 is fixed to an intermediate shaft 23 . The intermediate shaft 23 is connected to the input shaft 31 of the first planetary gear mechanism 30 via the coupling 24 .

The first planetary gear mechanism 30 includes a sun gear portion 33 formed on an input shaft 31, three planetary gears 34 meshing with the sun gear portion 33, a carrier pin 35 rotatably supporting each planetary gear 34, and Each planetary gear 34 is provided with an internal gear 36 with which it internally meshes. The first planetary gear mechanism 30 extracts the revolution of the three planetary gears 34 caused by the rotation of the sun gear portion 33 from the output member 37 to which the carrier pin 35 is fixed. The output member 37 is connected to the input shaft 41 of the second planetary gear mechanism 40 via a spline joint.
1 and 2, only one planetary gear 34 and one carrier pin 35 are shown. The same applies to planetary gears 44 and carrier pins 45 of the second planetary gear mechanism 40, which will be described later.

The second planetary gear mechanism 40 rotatably supports a sun gear portion 43 formed on an input shaft (sun gear shaft) 41, three planetary gears 44 meshing with the sun gear portion 43, and each planetary gear 44. It comprises a carrier pin 45 and an internal gear 46 with which each planetary gear 44 internally meshes. The second planetary gear mechanism 40 extracts the revolution of the three planetary gears 44 caused by the rotation of the sun gear portion 43 from the output member 47 to which the carrier pin 45 is fixed. The output member 47 is connected with the output shaft 49 via a spline joint. An end of the output shaft 49 is integrally fixed with an output pinion 49a that meshes with a gear (for example, a ring gear) provided on a driven member (not shown).

In the planetary gear device 1 having the above configuration, when the rotational force of the motor is input to the worm speed reduction mechanism 20, the worm pinion 21 and the worm gear 22 mesh with each other to reduce the speed at the first stage, and the input shaft of the first planetary gear mechanism 30 is reduced. 31.
When the input shaft 31 of the first planetary gear mechanism 30 rotates, the sun gear portion 33 formed on the input shaft 31 rotates, and the planetary gear 34 revolves inside the internal gear 36 . This revolution component is extracted from the output member 37 via the carrier pin 35 and transmitted to the input shaft 41 of the second planetary gear mechanism 40 via the spline joint.
In the second planetary gear mechanism 40 as well, the same deceleration action as in the first planetary gear mechanism 30 is performed, and the revolution of the planetary gear 44 is extracted from the output member 47 and transmitted to the output shaft 49 via the spline joint. When the output shaft 49 rotates, the output pinion 49a also rotates, and the rotational force is transmitted to the driven member connected to the output pinion 49a. Thus, the rotational force reduced by the worm speed reduction mechanism 20 and the two-stage simple planetary gear mechanism (the first planetary gear mechanism 30 and the second planetary gear mechanism 40) is output to the driven member.

[Tooth Surface Shape of Input Shaft of Second Planetary Gear Mechanism]
2 is an enlarged view of a main part of FIG. 1. FIG.
As shown in this figure, the input shaft (sun gear shaft) 41 of the second planetary gear mechanism 40 has a male spline portion 42 and a sun gear portion 43 coaxially.
Of these, the male spline portion (spline shaft) 42 is connected to the output member 37 of the first planetary gear mechanism 30 and has a plurality of first teeth that mesh with the female spline portion (spline hole) 38 of the output member 37. 42a (see FIG. 3(b)). On the other hand, the sun gear portion 43 has a plurality of second teeth 43a (see FIG. 3(b)) that mesh with the planetary gear 44. As shown in FIG.

The first teeth 42a of the male spline portion 42 and the second teeth 43a of the sun gear portion 43 have the same number of teeth and are formed in the same module. The male spline portion 42 is configured by extending in the direction. In other words, the input shaft 41 has teeth 41a axially connected (integrally formed) across the male spline portion 42 and the sun gear portion 43, of which the input side portion serves as the output gear portion. It is a first tooth 42a that meshes with the female spline portion 38 of the member 37, and the portion on the output side is a second tooth 43a that meshes with the planetary gear 44 (see FIG. 3(b)).
Note that although not particularly limited, the sun gear portion 43 (second tooth 43a) is subjected to a periodically changing load unlike the male spline portion 42 (first tooth 42a). It is preferable that the surface roughness (for example, arithmetic mean roughness Ra) of the tooth flank is smaller than that. For example, the sun gear portion 43 is more highly finished than the male spline portion 42 . For the same reason, the sun gear portion 43 (second tooth 43a) is subjected to high-frequency hardening, for example, only on the sun gear portion 43, so that the tooth flank of the male spline portion 42 (first tooth 42a) is less than that of the male spline portion 42 (first tooth 42a). is preferably high in hardness.

3(a) is an axial view of the teeth 41a of the input shaft 41, and FIG. 3(b) is a sectional view of the teeth 41a along line III--III in FIG. 3(a).
As shown in FIGS. 3A and 3B, the tooth thickness of the teeth 41a of the input shaft 41 varies in the axial direction (tooth width direction).
Specifically, in the present embodiment, for the purpose of improving tooth contact with the planetary gear 44, the sun gear portion 43 of the input shaft 41 has a substantially constant tooth thickness in the axial direction (illustrated by a broken line). The tooth trace (tooth surface) has been modified from. The sun gear portion 43 of this embodiment is crowned as a tooth trace modification. As a result, the sun gear portion 43 forms a crowning portion 43b whose tooth thickness gradually decreases toward both ends in the axial direction over the entire length in the axial direction. In the crowning portion 43b, the tooth thickness is distributed substantially symmetrically in the axial direction in the range where it meshes with the planetary gear 44, and the tooth thicknesses at both ends in the axial direction are substantially the same.
Note that the crowning portion 43b may be at least a portion of the sun gear portion 43. As shown in FIG. That is, it is sufficient that the sun gear portion 43 has the crowning portion 43b.

On the other hand, the male spline portion 42 of the input shaft 41 is not subjected to tooth trace modification processing (crowning). Therefore, the male spline portion 42 is a constant tooth thickness portion 42b having a substantially constant tooth thickness in the axial direction.
Note that the constant tooth thickness portion 42b may be at least a part of the male spline portion 42. As shown in FIG. That is, it is sufficient that the male spline portion 42 has a constant tooth thickness portion 42b (if the axial end portion of the male spline portion 42 is chamfered, the chamfered portion is excluded).

Thus, in this embodiment, the sun gear portion 43 has the crowning portion 43b, and the male spline portion 42 has the constant tooth thickness portion 42b. This improves the meshing of the sun gear portion 43 without deteriorating the meshing of the male spline portion 42 . That is, it is possible to modify the tooth trace of the sun gear portion 43 while suppressing deterioration of the meshing of the male spline portion 42 .
More specifically, in normal tooth trace modification, the entire tooth flank is machined along the face width direction using a grinding wheel. In this case, the tooth shape on the male spline side has a curved shape due to the extension of the crowning portion, as shown by the two-dot chain line in FIG. There is a risk that the meshing will deteriorate (play etc. will occur).
In this regard, in the present embodiment, crowning is performed so that the sun gear portion 43 has a crowning portion 43b and the male spline portion 42 has a constant tooth thickness portion 42b. That is, the tooth trace of the sun gear portion 43 is modified while suppressing deterioration of meshing of the male spline portion 42 (occurrence of backlash). As a result, the backlash of the male spline portion 42 causes misalignment of the gears of the planetary speed reduction portion, and there is a risk of uneven contact of the gears and damage to the tooth surfaces. , the risk of uneven contact and tooth surface damage can be reduced.

The male spline portion 42 may not have the constant tooth thickness portion 42b as long as the amount of change in tooth thickness in the axial direction is smaller than that of the crowning portion 43b. Here, the "tooth thickness change amount (in the axial direction)" of the crowning portion 43b refers to the relative tooth thickness between the axial center of the crowning portion 43b having the largest tooth thickness and the axial end portion having the smallest tooth thickness. Refers to the amount of change in thickness ΔS (in the case of one side, twice that in the case of both sides). Similarly, the "tooth thickness variation (in the axial direction)" of the male spline 42b is the relative variation in tooth thickness between the portion of the male spline portion 42b where the tooth thickness is the largest and the portion where the tooth thickness is the smallest. In this embodiment, since the tooth thickness is constant, the tooth thickness change amount is "0". With such a configuration, the same effect as described above can be obtained. Therefore, for example, as shown in FIG. 4A, the tooth thickness may be uniform from the axial end of the sun gear portion 43 (crowning portion 43b) where crowning is completed to the male spline portion 42 side.

[Technical effect of the present embodiment]
As described above, according to the planetary gear device 1 of the present embodiment, the input shaft (sun gear shaft) 41 has the male spline portion 42 formed by axially extending each tooth portion of the sun gear portion 43. The sun gear portion 43 has a crowning portion 43b whose tooth thickness gradually decreases toward both ends in the axial direction, and the male spline portion 42 has a smaller tooth thickness change in the axial direction than the crowning portion 43b. .
Therefore, it is possible to modify the tooth trace of the sun gear portion 43 while suppressing deterioration of the meshing of the male spline portion 42 . As a result, the backlash of the male spline portion 42 causes misalignment of the gears of the planetary speed reduction portion, and there is a risk of uneven contact of the gears and damage to the tooth surfaces. , the risk of uneven contact and tooth surface damage can be reduced.

Further, according to the planetary gear device 1 of the present embodiment, the male spline portion 42 has the constant tooth thickness portion 42b having a constant tooth thickness in the axial direction.
As a result, it is possible to modify the tooth trace of the sun gear portion 43 while further suppressing deterioration of meshing of the male spline portion 42 .

[Modification]
In the above-described embodiment, the change in the tooth thickness of the male spline portion 42 of the input shaft 41 is suppressed to suppress deterioration of meshing with the female spline portion 38 . However, the tooth thickness of the female spline portion 38 may be changed in the axial direction according to (corresponding to) the change in the tooth thickness of the male spline portion 42 in the axial direction.
More specifically, as shown in FIG. 4(b), the change in the axial direction depends on the tooth thickness of the first tooth 42a of the male spline portion 42 and the width of the tooth space 38a of the female spline portion 38 meshing therewith. The rates may correspond to each other. Here, the fact that the tooth thickness of the first tooth 42a and the width of the tooth groove 38a correspond to each other in the rate of change in the axial direction means that the rate of change in the axial direction substantially coincides at corresponding axial positions. (within a predetermined error range).

In this case, the tooth trace modification of the input shaft 41 (teeth 41a) may be performed by machining the crowning portion 43b and the male spline portion 42 so that the change in tooth thickness in the axial direction continues smoothly. For example, the male spline portion 42 may be linearly machined while maintaining the tooth thickness change rate of the input side end portion of the crowning portion 43b. In other words, the tooth thickness of the crowning portion 43b may change in a curved line in the axial direction, and the tooth thickness of the male spline portion 42 may change linearly in the axial direction. By keeping the tooth thickness change rate constant (or not changing it greatly), machining can be performed relatively easily.

Even when the tooth thickness of the female spline portion 38 is changed in accordance with the change in the tooth thickness of the male spline portion 42 in this way, the engagement between the male spline portion 42 and the female spline portion 38 is the same as in the above-described embodiment. It is possible to modify the tooth trace of the sun gear portion 43 while suppressing the deterioration of (occurrence of backlash).

[others]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.
For example, in the above embodiment, the present invention is applied to the input shaft (sun gear shaft) 41 of the second planetary gear mechanism 40 of the second stage, but the present invention is applied to the first planetary gear mechanism of the first stage. 30 input shaft (sun gear shaft) 31 is also applicable. That is, the intermediate shaft (output shaft) 23 (or the output shaft of the motor) of the worm speed reduction mechanism 20 and the input shaft 31 of the first planetary gear mechanism 30 are connected by a spline, and the spline portion and the sun gear portion 33 are connected to each other. The structure of the present invention may be applied. Moreover, it can be widely applied to planetary gear devices having a sun gear shaft, and the number of stages of the speed reduction mechanism and the type of speed reduction mechanism to be combined are not particularly limited.

Further, in the above embodiments, a simple planetary gear mechanism was described as an example of the planetary gear mechanism, but the planetary gear device according to the present invention is not limited to the simple planetary gear mechanism, and the sun gear portion and the spline portion are coaxial. It is widely applicable to planetary gear trains (mechanisms) arranged thereon.

Further, the planetary gear device according to the present invention can be applied to various speed reducers such as a yaw drive speed reducer for a wind power generator, a swing bearing speed reducer for an excavator, and a planetary speed reducer for a robot.
In addition, the details shown in the above embodiments can be changed as appropriate without departing from the scope of the invention.

1 Planetary gear device 30 First planetary gear mechanism (previous reduction mechanism)
37 Output member (previous stage shaft)
38 female spline portion 38a tooth groove 40 second planetary gear mechanism 41 input shaft (sun gear shaft)
41a Tooth 42 Male spline portion 42a First tooth 42b Constant tooth thickness portion 43 Sun gear portion 43a Second tooth 43b Crowning portion 44 Planetary gear Ax Central axis ΔS Tooth thickness variation

Claims (9)

A planetary gear device comprising a sun gear shaft having a sun gear portion and a planetary gear meshing with the sun gear portion,
The sun gear shaft has a male spline portion for coupling with the front stage shaft, and the male spline portion is formed by extending each tooth portion of the sun gear portion in the axial direction,
The sun gear portion has a crowning portion whose tooth thickness gradually decreases toward both ends in the axial direction,
The male spline portion has a smaller amount of change in tooth thickness in the axial direction than the crowning portion,
Planetary gearing. The male spline portion has a constant tooth thickness portion having a constant tooth thickness in the axial direction,
A planetary gear device according to claim 1. A planetary gear device comprising a sun gear shaft having a sun gear portion, a planetary gear meshing with the sun gear portion, and a pre-stage shaft connected to the sun gear shaft,
The sun gear shaft has a male spline portion connected to the front stage shaft, and the male spline portion is configured by extending each tooth portion of the sun gear portion in the axial direction,
The sun gear portion has a crowning portion whose tooth thickness gradually decreases toward both ends in the axial direction,
The male spline portion has a tooth thickness that changes in the axial direction continuously from the crowning portion,
In the front shaft, a female spline portion that meshes with the male spline portion has a tooth thickness that changes in the axial direction in accordance with a change in tooth thickness of the male spline portion in the axial direction.
Planetary gearing. The crowning portion has a tooth thickness that changes in a curve in the axial direction,
The male spline portion has a tooth thickness that varies linearly in the axial direction,
A planetary gear device according to claim 3. In the crowning portion and the male spline portion, changes in tooth thickness in the axial direction are smoothly continuous with each other.
A planetary gear device according to claim 3 or 4. The front shaft is an output member of the front speed reduction mechanism,
The planetary gear device according to any one of claims 1 to 5. The crowning portion has the same tooth thickness at both ends in the axial direction in a range that meshes with the planetary gear.
A planetary gear device according to any one of claims 1 to 6. The sun gear portion has a tooth surface roughness smaller than that of the male spline portion,
A planetary gear device according to any one of claims 1 to 7. The sun gear portion has a tooth surface hardness higher than that of the male spline portion,
The planetary gear device according to any one of claims 1 to 8.

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