JP2003074646A - Internal gear structure for internal meshing planetary gears - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide planetary reduction gear that reduces a backlash and eliminates increase in pulsation and noise due to an inappropriate meshing. SOLUTION: A planetary structure is so designed that planet gears 210 (210A to 210C) with external teeth are in internal contact with an internal gear 280 with internal teeth (roller pins) 284. A body 282 of the internal gear 280 is coaxially provided with a first and a second ringed slit 290 and 292 from opposite axial sides.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal gear structure of an internally meshing planetary gear device having a planetary gear structure in which a planetary gear having external teeth is inscribed in an internal gear having internal teeth.

[0002]

2. Description of the Related Art Conventionally, a planetary gear structure in which a planetary gear having external teeth is inscribed on the inner peripheral side of an internal gear having internal teeth has been widely known as, for example, a speed reducing structure of a speed reducer.

FIG. 3 shows a conventional example of this type of speed reducer.

The speed reducer G is used, for example, for driving an industrial robot, and its planetary gear 1 is used.
0 internally meshes with the internal gear 12 while eccentrically swinging,
So-called eccentric rocking type planetary gear structure (International classification F1
6H 1/32 belonging to the planetary gear structure).

The input shaft 16 of the speed reducer G has a phase difference of 120 °.
The three eccentric bodies 18A to 18C are integrally formed. Each eccentric body 18A-18C has a bearing 20A-
20C through (3) planetary gears 10 (10A
10C) is attached.

External teeth such as a trochoidal tooth profile and an arc tooth profile are formed on the outer circumference of the planetary gears 10A to 10C. The three planetary gears 10A to 10C are internally meshed with the aforementioned (one) internal gear 12 that is long in the axial direction.

The internal gear 12 has a structure in which a plurality of roller pins 12B each having internal teeth are rotatably incorporated on the inner peripheral side of an internal gear main body 12A which also serves as a casing.

Each of the planetary gears 10A to 10C has a plurality of inner roller holes 22A in the axial direction at appropriate intervals in the circumferential direction.
22C are formed, and the inner roller 24 and the inner pin 26 are inserted. The inner pin 26 is connected to the carrier 28 at one end side in the axial direction thereof, and the carrier 28 is rotatably supported by the first and second casings 32 and 34 via a cross roller 30. The first and second casings 32,
34 holds the internal gear main body 12A of the internal gear 12 (which also serves as a casing) together with the third casing 36, and is integrated by bolts 38 and 40 penetrating each member.

Reference numeral 42 in the drawing is a bolt hole for attaching the first and second casings 32 and 34 to a mating machine (not shown) or a fixing member. In addition, the input shaft 1
6 is rotatably supported by the carrier 28 and the third casing 36 via a pair of bearings 44, 46.

The speed reducer G is a planetary gear 1 when the internal gear 12 (first to third casings 32 to 36) is fixed.
It can also be used as a speed reducer for extracting rotations corresponding to the rotation components of 0A to 10C from the carrier 28, and outputs rotation of the internal gear 12 when rotation of the planetary gears 10A to 10C (rotation of the carrier 28) is restricted. It can also be used as a reducer. In addition, each planetary gear 10
The swinging component is absorbed by the loose fit between the inner roller holes 22A to 22C of the planetary gears 10A to 10C and the inner roller 24.

On the other hand, as shown in FIG. 4, two carriers 128A and 128B are provided on both sides of the planetary gears 110A and 110B in the same configuration, and two planetary gears 11 are provided.
A configuration in which 0A and 110B are so-called both-sided support is also known.

In the case of this reduction gear G2, the internal gear 112
Is a plurality of roller pins 1 each of which has internal teeth on the inner peripheral side of one internal gear main body 112A that also serves as a casing.
12B is rotatably incorporated.
The input shaft 116 is supported by the first and second carriers 128A and 128B via a pair of bearings 144 and 146,
The first and second carriers 128A and 128B are supported by the internal gear main body 112A (also serving as a casing) via angular roller bearings 130A and 130B.

Reference numeral 150 is the first and second carriers 1.
It is a carrier pin that connects 28A and 128B.

Since other configurations are basically the same as those of the above-mentioned conventional example, only corresponding portions in the drawing are given the same reference numerals in the last two digits, and the duplicated description will be omitted.

[0015]

[Problems to be Solved by the Invention] In recent years, as the performance of products to be manufactured has become higher, the driving performance of industrial robots for manufacturing these products is required to have higher precision. Is becoming. The driving performance of an industrial robot largely depends on the basic rotation performance and backlash characteristics of the mounted reducer.

In the case of the planetary gear reducer, generally, there are a plurality of planetary gears, and each planetary gear moves in a complex manner in which the revolution and the rotation are intertwined in the inner circumference of the internal gear. Therefore, a machining error or an assembly error of each gear has a great influence on the smoothness of rotation, and causes a pulsation and an increase in noise.

Further, in order to reduce the backlash which causes deterioration of the position accuracy when the rotation direction is reversed, it is necessary to make the design clearance between the teeth as close to zero as possible. Even if the assembly error occurs to the maximum, it must be possible to rotate smoothly, and in this sense, these errors must be reduced as much as possible.

In particular, in the case of the planetary gear structure of the "eccentric rocking type in which an internal gear is internally meshed while eccentrically rocking" as the structure of the speed reducer described above, there are severe requirements for machining errors and assembly errors.

However, improving the machining accuracy and the assembling accuracy is accompanied by an extremely large cost increase, and the design is made so that the clearance between the gears approaches zero (the backlash is reduced as much as possible) by these improvements. Then,
Assembling becomes difficult, which causes a new decrease in productivity.

The present invention has been made in order to solve such a conventional problem, and by structurally devising it, the rotational performance can be improved even if a machining error and an assembly error of the same level as the conventional one remain. An object of the invention is to provide a planetary gear structure capable of improving and reducing backlash.

[0021]

DISCLOSURE OF THE INVENTION The present invention is an internally meshing planetary gear device having a planetary gear structure in which an internal gear having internal teeth is inscribed with a planetary gear having external teeth. In the internal gear structure of an internally meshing planetary gear device directly formed integrally with the internal gear main body, a slit cut in the internal gear main body so as to be coaxial with the axis of the internal gear. By forming the, the above-mentioned problems are solved.

Generally, the internal gear of this type of planetary gear structure is required to bear the amplified transmission torque after deceleration or its reaction force in view of its function, and accordingly, appropriate strength or rigidity is required. . Therefore, conventionally, in many cases, the main body of the internal gear serves also as the casing as in the above-described example, and has high strength and rigidity.

As described above, the internal gear formed of a material having high strength or rigidity naturally has a small amount of bending.
Having less bending yields good results when adopting the conventional method of improving rotational performance or reducing backlash by improving processing accuracy and assembly accuracy, but as mentioned above, this method also reduces costs. And increase the difficulty of assembly.

According to the present invention, the performance of the reduction gear is improved by the conventional method, that is, the machining error or the assembly error itself is not reduced, but the existing error is caused by bending the internal gear itself. Absorbs well.

On the other hand, on the other hand, if the internal gear is simply made of a material having low rigidity or its radial thickness is reduced in order to obtain "deflection", the reduction gear of The "transmission torque capacity" itself is reduced, and the value of the product is reduced accordingly.

Therefore, the present invention eliminates this problem by adopting a construction in which a slit cut coaxially with the axis of the internal gear is formed in the internal gear main body.

According to the present invention, the rotational performance can be further improved while allowing the same processing error or assembly error as in the conventional case. Further, it is possible to further reduce the backlash and ensure the ease of assembling as compared with the conventional case.
Furthermore, since the backlash can be reduced, the positioning accuracy can be maintained high even when it is used in applications such as industrial robots that repeat forward and reverse rotation, and rattling noise during reverse rotation is also reduced. it can.

The present invention is not limited to the internal mesh planetary gear device in which the internal teeth are directly formed integrally with the internal gear body, but the internal teeth are rotatably incorporated in the internal gear body. The same can be applied to the internal gear structure of the internally meshing planetary gear device including a plurality of roller pins. Rather, in this case, the roller pin that is long and hard in the axial direction constitutes each inner tooth while obtaining a sufficient amount of deflection (in particular, the amount of deflection in the radial direction), and therefore each tooth profile itself It becomes possible to prevent the distortion and to reduce the influence of the bending in the circumferential direction as much as possible.

Further, according to the present invention, as the slit, at least one slit on one end side cut in the axial direction of the internal gear and the other end side in the axial direction of the internal gear are cut. If two pairs of slits (including one slit at the other end side) are formed, the amount of axial deflection of the internal gear can be made uniform, and a plurality of planetary gears ( When used in multiple rows, each planet gear can evenly share the transfer torque.

Further, in the present invention, the amount of bending of the internal gear body at the rated output at the meshing portion of the planetary gear caused by the presence of the slit is 0.5 times to 3 times the machining tolerance of the planetary gear. When set to 0.0 times, it is possible to sufficiently absorb the processing error and the assembly error of each element including the internal gear and the planetary gear, and the internal gear flexes more than necessary. Since it does not occur, it becomes possible to minimize the problems caused by bending.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of an embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a longitudinal sectional view corresponding to FIG. 3 or FIG. 4 showing the entire structure of a speed reducer to which the present invention is applied, and FIG. 2 is an enlarged sectional view of a main part thereof.

The input shaft 216 of the speed reducer 214 has a phase difference of 1
Three 20 ° eccentric bodies 218A to 218C are integrally formed. Each of the eccentric bodies 218A to 218C is provided with three planetary gears 2 via bearings 220A to 220C.
10 (210A to 210C) are attached. The reason why the three planetary gears 210A to 210C are arranged in a double row is mainly to increase the transmission capacity, maintain the strength, and maintain the rotational balance.

On the outer circumference of the planetary gears 210A to 210C,
The trochoidal tooth profile (a circular tooth profile is acceptable) is formed. The planetary gears 210A to 210C are internally meshed with the internal gear 280 according to the present invention.

The internal gear 280 comprises an internal gear body 282.
And a plurality of roller pins 284 each of which is rotatably incorporated in the internal gear main body 282 and each of which constitutes an internal tooth.

The internal gear main body 282 is substantially the same in overall shape as the conventional internal gear 12, and has a sufficient thickness. The internal gear main body 282 is sandwiched between the first and second casings 232 and 234 and the third casing 236, and has a bolt (not shown) (bolt hole 239 in the example shown).
(Only shown) are firmly integrated. Therefore, the transmission torque of the internal gear 280 or its reaction torque can be sufficiently transmitted and held.

Further, the innermost peripheral side of the internal gear main body 282 is provided with an internal tooth holding portion 286, which can rotatably hold the roller pin 284. The roller pin 284 is formed of a material harder than the internal gear main body 282 including the internal tooth holding portion 286, is rotatably incorporated on the inner peripheral side of the internal tooth holding portion 286, and each of them is internally Make up the teeth.

Here, in the internal gear main body 282, a first slit 290 cut coaxially with the axial center O1 of the internal gear 280 from the end surface (one end side in the axial direction) 282A on the second casing 234 side, The second slit 29 cut from the end face (the other end in the axial direction) 282B on the third casing 236 side coaxially with the axis O1 of the internal gear 280 on the inner peripheral side thereof.
2 is formed.

Each of the first and second slits 290 and 292 is
Almost ring-shaped, its height (thickness in the radial direction) H
2 and H3 (H2 = H3 in this embodiment) are set to heights of about 0.03 to 0.1, respectively, when the pitch circle radius of the roller pin 284 of the internal gear is H1. .

The degree of bending near the internal teeth (roller pin) 284 is determined by the height H of the first and second slits 290 and 292.
2, the higher H3 is, the first and second slits 290, 29
The longer the axial lengths L1 and L2 of 2, the second slit 2
The lower the height H4 between 92 and the roller pin 284 is,
The lower the height H5 between the first and second slits 290 and 292, and the larger the elastic coefficient of the internal gear main body 282, the larger.

In this embodiment, since the first and second slits 290 and 292 are cut from both sides of the internal gear main body 282, the difference in bending depending on the axial position is relatively small. However, the deflection is still slightly different depending on the axial position. Therefore, by adjusting the above elements or parameters in a predetermined direction, each planetary gear 210A can be adjusted.
It is set so that the deflection due to 210C becomes almost even.

More specifically, the first and second slits 2
Due to the existence of 90 and 292, the three planetary gears 210A to
In order to make the amount of deflection δ at the rated output at each meshing portion where 210C abuts to be approximately twice the machining tolerance of the planetary gears 210A to 210C, use FEM analysis or the like to set the above-mentioned elements or parameters to appropriate values. Adjust to.

A preferable range of the flexure amount (set flexure amount) δ is 0.5 which is a machining tolerance of the planetary gears 210A to 210C.
The range is from twice to three times. If the bending amount δ is within this range, it is possible to satisfactorily absorb the processing error and assembling error of each element, and since it does not bend more than necessary, the rigidity and durability of the internal gear 280 as a whole are improved. You can also secure the sex. In addition, more preferably, the planetary gears 210A to 21
The machining tolerance of 0C is in the range of 1.5 to 2.5 times to 2.5 times, and the best is almost twice as in this embodiment.

Reference numeral 262 in the figure denotes an oil seal, which seals between the first casing 232 and the carrier 228A and serves to seal the other end of the speed reducer 214.

Since other structures are basically the same as those of the conventional example shown in FIG. 3 or FIG. 4, the same or similar portions in the drawing are designated by the same last two digits. Stop and duplicate description will be omitted.

Next, the operation of this embodiment will be described.

Regarding the basic deceleration action in which the rotation of the input shaft 216 can be taken out as a deceleration output from either the first or second casing 232 or 234 integrated with the carrier 228 or the internal gear 280, There is no difference from the past.

The speed reducer 214 may take out, as an output, the rotation corresponding to the rotation component of the planetary gear 210 when the internal gear 280 is fixed, or the internal gear when the rotation of the planetary gear 210 is restricted. The rotation of the gear 280 may be taken out as an output. For example, when the number of teeth of the planetary gear 210 is N and the number of teeth of the internal gear 280 is N + α, the reduction ratio (gear ratio) i = α / N is obtained in the former drive system, and α / N in the latter case. (N + α) is obtained. Note that a speed increaser can also be configured by reversing the input and output relationships.

Here, the internal gear 280 is its main body 282.
Since the first and second slits 290 and 292 are formed on the outer surface of the planetary gear 210,
Even if there is almost no clearance in the mesh with the internal teeth (roller pin) 284 of 80, due to the bending deformation of the internal gear 280, good assembling performance can be secured. In addition, the amount of deformation in meshing during transmission of the set torque is approximately 2 of the machining tolerance of the planetary gears 210A to 210C by FEM analysis.
Since it is set to double, even if a predetermined processing error occurs in the manufacturing process, this will be corrected.
The internal tooth holding portion 286 of 82 can be favorably absorbed by the bending (deformation), and smooth rotation and quietness can be secured.

Therefore, although the level of processing error and assembly error is the same as in the conventional case, since the backlash is small, the rotation angle error and rattling noise at the time of reverse rotation are small, and the assembly is easy, smooth and quiet. A speed reducer that can rotate can be obtained.

Further, in the internal gear main body 282, the first and second slits 290, 282A, 282B are arranged from both axial sides 282A, 282B.
292 is cut, so three external gears 210A
It is easy to adjust so that the bending amounts (displacements) of the internal tooth holding portions 286 in the meshing portions with the gears 210C to 210C become equal, and the transmission torques that are carried by the external gears 210A to 210C can be made substantially equal. Therefore, for example, only the specific planetary gear 210 does not take an excessive torque, and the deformation amount of only the specific planetary gear 210 becomes abnormally large, so-called ratcheting (tooth does not mesh with each other and slips). It is also possible to prevent the occurrence of a phenomenon).

Further, in this embodiment, the internal teeth are formed of a material harder than the internal gear main body 282, and are constituted by a plurality of roller pins 284 rotatably incorporated on the inner peripheral side of the internal gear main body 282. Because it is done
While the sufficient bending amount (especially the bending amount in the radial direction) is obtained, the roller pin 284 that is long and hard in the axial direction constitutes each inner tooth, so that each tooth profile itself is prevented from being distorted. As a result, it is possible to reduce the influence of the bending in the circumferential direction as much as possible.

Incidentally, the first and second slits 290 and 292.
In this embodiment, one slit (two slits in total) is formed from both sides in the axial direction of the internal gear main body 282, but even if only one slit is provided, a corresponding effect can be obtained. On the contrary, it may be three or more. However, when forming a plurality, it is preferable to make the number even and to cut alternately from both sides in the axial direction of the internal gear main body, because variations in the bending amount δ at each axial position can be reduced as much as possible.

Further, in the above-mentioned embodiment, the example in which the internal teeth are of the roller pin type is shown, but the object of application of the present invention is not limited to this type of structure, but is applied to the internal gear body. It is naturally applicable to the type in which the internal teeth are directly formed.

[0055]

According to the present invention, it is possible to absorb the influence of machining error and assembly error by the bending of the internal gear,
The backlash can be further reduced and the ease of assembly and the smoothness of rotation can be ensured while the processing accuracy or the assembly accuracy is the same as the conventional one. As a result, it is possible to effectively prevent the rattling noise from being generated during reverse rotation, the increase in noise due to poor meshing, and the occurrence of rotational unevenness.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a speed reducer for an industrial robot to which the present invention is applied.

FIG. 2 is an enlarged view of a main part near the internal gear of FIG.

FIG. 3 is a vertical sectional view showing an example of a conventional speed reducer of this type.

FIG. 4 is a vertical sectional view showing another conventional example.

[Explanation of symbols]

40 ... bolt 214 ... reducer 218A to 218C ... Eccentric body 210 (210A to 210C) ... Planetary gear 230 ... Cross roller (bearing) 280 ... Internal gear 282 ... Internal gear body 284 ... Roller pin 286 ... Internal tooth holder 290, 292 ... First and second slits

Claims (4)

[Claims] 1. An internally meshing planetary gear device comprising a planetary gear structure in which a planetary gear having external teeth is inscribed in an internal gear having internal teeth, the internal teeth being directly integrated with an internal gear body. In the internal gear structure of the internally meshing planetary gear device formed in, a slit cut coaxially with the axis of the internal gear is formed in the internal gear body. Internal gear structure of internally meshing planetary gear unit. 2. A planetary gear structure in which a planetary gear having external teeth is inscribed in an internal gear having internal teeth, the internal teeth being constituted by a plurality of roller pins incorporated in an internal gear body. In an internal gear structure of a contact mesh planetary gear device, an internal mesh planetary gear device characterized in that a slit cut coaxially with the axis of the internal gear is formed in the internal gear body. Internal gear structure. 3. The slit according to claim 1, wherein at least one slit is cut from at least one axial end of the internal gear and the other axial end of the internal gear is cut. An internal gear structure of an internally meshing planetary gear device, characterized in that two slits, which are the other end side slits, are formed. 4. The machining tolerance of the planetary gear according to any one of claims 1 to 3, wherein a deflection amount at a rated output at a meshing portion of the internal gear main body of the internal gear, which is caused by the presence of the slit, at a rated output. The internal gear structure of the internally meshing planetary gear device is characterized by being set to 0.5 times to 3.0 times.