JP2003065403A - Epicyclic gearing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epicyclic reduction gear involving a small backlash and free of pulsation and a noise increase due to poor performance of meshing. SOLUTION: The epicyclic gearing structure is configured so that a planet gear 210 (210A and 210B) having outer teeth is inscribed with an internal gear 270 having inner teeth (roller pins) 274, wherein the internal gear 270 is structured as supported by a cross roller (bearing) 230 in a region S on one side in axial direction of the planet gear 210 and furnished with a flange part 272 capable of holding the transmission torque of the internal gear 270, and with a flexible inner tooth holding part 276 extended cylindrically from the flange part 272 in its axial direction in the cantilever form and having roller pins 274 on its internal circumferential surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to 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.

A conventional example of this type of speed reducer is shown in FIG.

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. 5, the two planetary gears 11 are provided with two carriers 128A and 128B on both sides of the planetary gears 110A and 110B with the same structure.
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]

SUMMARY OF THE INVENTION The present invention provides a planetary gear structure in which an internal gear having internal teeth is inscribed with a planetary gear having external teeth, wherein the internal gear has one axial side of the planetary gear. A flange portion supported by a bearing in a region and capable of holding the transmission torque of the internal gear; and a cylindrical portion extending from the flange portion in a cantilevered state in the axial direction and having the inner periphery on the inner periphery thereof. By providing a flexible inner tooth holding portion having teeth, the above problem is 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, in the present invention, the internal gear has a (strong) flange portion capable of holding the transmission torque of the internal gear,
This problem has been solved by forming a cylindrical internal cantilever from the flange in a cantilevered manner and having a flexible internal tooth holding portion having internal teeth on its inner circumference.

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.

In the present invention, the internal tooth holding portion is cantilevered from the flange portion in order to facilitate the construction and ensure good bending characteristics. In a part in the axial direction (for example, the end part on the opposite flange side),
It is more preferable to form a thick portion for increasing the rigidity near the portion. As a result, for example, when a plurality of planetary gears are provided in parallel, the amount of bending of the internal tooth holding portion of the portion where each planetary gear exists (the portion that meshes) can be made uniform, and each planetary gear can be transmitted evenly. You will be able to take charge of the torque.

The inner tooth holding portion is formed of an inner tooth holding portion main body and a material harder than the inner tooth holding portion main body, and is rotatably incorporated on the inner peripheral side of the inner tooth holding portion. ,
When each of them is composed of a plurality of roller pins that form the inner teeth, a roller pin that is long and hard in the axial direction can be obtained while obtaining a sufficient amount of bending (particularly, the amount of bending in the radial direction). Since each internal tooth is configured, it is possible to prevent the tooth profile itself from being distorted, and it is possible to reduce the influence of bending in the circumferential direction as much as possible.

Further, the planetary gear structure is a swing type planetary gear in which the planetary gear internally meshes with the internal gear while eccentrically swinging, and the planetary gear is fixed when the internal gear is fixed. A planetary gear structure of a oscillating inner meshing type that outputs either the rotation corresponding to the rotation component of the planetary gear or the rotation of the internal gear when the rotation of the planetary gear is restricted, and the planetary gear When the gear ratio obtained by the structure is i, the eccentricity of the planetary gear is e, and the pitch circle radius of the internal teeth of the internal gear is R, then (i + 1) · e / R ≧
When each parameter is set so that 0.7 is satisfied (more preferably 0.8 or more is satisfied), as will be described later, the adverse effect due to the presence of bending is minimized. You will be able to suppress.

The amount of bending of the internal gear holding portion is 0.5 to 3 times the machining tolerance of the planetary gear, in terms of the amount of bending at the rated output at the meshing part of the internal gear of the internal gear holding portion. ．
It is recommended to set it to 0 times.

As a result, it is possible to secure further rotation stability (because the inner tooth holding portion does not bend more than necessary) while properly absorbing the processing error.

[0033]

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 vertical sectional view corresponding to FIG. 4 or 5 showing the entire structure of a speed reducer to which the present invention is applied.

The input shaft 216 of the speed reducer 214 has a phase difference of 1
Two 80 ° eccentric bodies 218A and 218B are integrally formed. Each of the eccentric bodies 218A and 218B has two planetary gears 2 through bearings 220A and 220B.
10 (210A, 210B) are attached. The reason why the two planetary gears 210A and 210B are arranged in a double row is mainly to increase the transmission capacity, maintain the strength, and maintain the rotational balance.

On the outer periphery of the planetary gears 210A and 210B,
The trochoidal tooth profile (a circular tooth profile is acceptable) is formed. The planetary gears 210A and 210B are internally meshed with the internal gear 270 according to the present invention.

The internal gear 270 is the planet gear 210A, 2
In a region S on one axial side (left side in the example of the drawing) of 10B, a flange portion 272 supported by a cross roller (bearing) 230 and capable of holding the transmission torque of the internal gear 270, and the flange portion 272. A flexible internal tooth holding portion 2 having a roller pin 274 extending in a cantilevered state in the axial direction in a cantilevered manner and having internal teeth forming internal teeth.
And 76.

The flange portion 272 is integrated with the first and second casings 232 and 234 via unillustrated bolts (only the bolt hole 239 is shown in the illustrated example), and is enlarged in FIG. As shown, the length L1 in the axial direction and the length R1 in the radial direction (partly R2) are provided. Therefore, the transmission torque of the internal gear 270 or the reaction torque thereof can be sufficiently retained.

On the radially inner side of the flange portion 272, the axial center C2 is the bolt hole 239 of the flange portion 272.
It is slightly shifted from the axial center C1 in the vicinity,
Moreover, by setting the axial length L2 to be short,
(L2 <L1) First, it is considered that the inner tooth holding portion 276 can be relatively easily bent at this portion.

The internal tooth holder 276 is the internal tooth holder body 27.
8 and a plurality of members each of which is formed of a harder material than the inner tooth holding portion main body 278 and is rotatably incorporated on the inner peripheral side of the inner tooth holding portion main body 278 and each of which constitutes an inner tooth. Roller pin 274.

The thickness of most of the inner tooth holder main body 278 in the axial direction is suppressed to D1 and has flexibility.

The internal tooth holder 276 (specifically, the main body 2 thereof)
In part (78) in the axial direction, that is, on the end portion on the side opposite to the flange side in the axial direction, a thick portion 280 for increasing the rigidity in the vicinity of the end portion on the side opposite to the flange is formed. This is for making the flexure of the internal tooth holding portion 276 with respect to the external gear 210A, 210B substantially equal, and at the same time, by reinforcing the end of the internal tooth holding portion 276 on the side opposite to the flange, The opposite flange end and the carrier 228B
This is for ensuring the sealing performance of the oil seal 260 arranged between the and.

Specifically, the axial length L3 and the radial thickness D2 or D3 of the end portion on the side opposite to the flange are 2
By FEM analysis, etc., so that the amount of deflection at the rated output at each meshing part where the planetary gears 210A and 210B are in contact is approximately equal to twice the machining tolerance of the planetary gears 210A and 210B. , Is set to an appropriate value.

The speed reducer 214 has an internal gear 270.
The rotation corresponding to the rotation component of the planetary gear 210 when the gear is fixed may be taken out as an output, or the planetary gear 210 may be extracted.
The rotation of the internal gear 270 when the rotation of the internal gear is regulated 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 270 is N + α, the reduction ratio (gear ratio) i = α / N is obtained in the former drive system,
In the latter case, α / (N + α) is obtained. Note that a speed increaser can also be configured by reversing the input and output relationships.

In this embodiment, when the reduction ratio is i, the eccentricity of the planetary gear 210 is e, and the pitch circle radius of the internal teeth (roller pins) 274 of the internal gear 270 is R, (i +
1) · e / R = 0.9 is established.

Reference numeral 262 in the figure is a carrier 228B.
The oil seal 264 serves as a seal on one side in the axial direction of the speed reducer 214 together with the oil seal 260 described above by sealing between the oil seal 264 and the input shaft 216.
Seals the first casing 232 and the carrier 228A 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. 4 or 5, the same or similar portions in the drawing are denoted by the same last two digits. Stop and duplicate description will be omitted.

Next, the operation of this embodiment will be described.

The rotation of the input shaft 216 causes the rotation of the carrier 228A,
The basic deceleration action that can be taken out as the deceleration output from either the first or second casing 232 or 234 integrated with the internal gear 270 is not particularly different from the conventional one.

Here, the internal gear 270 is the flange portion 27.
2 and the flexible inner tooth holding portion 276, the outer teeth of the planetary gear 210 and the inner teeth (roller pin) 274 of the inner gear 270 are designed to have a gap in design. Even if it does not exist, it is possible to secure good assembling property by the bending deformation of the internal gear 270. Further, since the amount of deformation in meshing at the time of transmitting the set torque is set to be equal to the machining tolerance by FEM analysis, even if a predetermined machining error occurs in the manufacturing process, this is caused by the bending of the internal tooth holding portion 276. It can be satisfactorily absorbed by (deformation). Therefore, even though the level of processing error and assembly error is the same as the conventional one, the backlash is small, so that the rotation angle error and rattling noise at the time of reverse rotation are small, and the speed reducer is easy to assemble and can rotate smoothly. Can be obtained.

Further, a thick portion 280 for increasing the rigidity of the non-flange side end portion of the inner tooth holding portion 276 is provided at a meshing portion with the two external gears 210A and 210B. Since the inner tooth holding portions 276 are formed so that the bending amounts (deformation amounts) of the inner tooth holding portions 276 are equal, that is, the transmission torques that the external tooth gears 210A and 210B bear are almost equal, only the planet gear 210A on the flange side is formed. Does not take an excessive torque, and the modified example of the planetary gear 210B on the opposite flange side becomes abnormally large, causing so-called ratcheting (a phenomenon in which teeth slide without engaging with each other). It can be prevented.

Further, when the reduction ratio (gear ratio) is i, the eccentric amount of the planetary gear 210 is e, and the pitch circle radius of the internal teeth (roller pins) 274 of the internal gear 270 is R, (i +
1) Since each parameter is set so that e / R is 0.9 (0.7 or more), as shown in FIG. 3B, the outer teeth of the planetary gear 210 and the roller pin 274 are It is possible to secure a large value (α1 <α2) as the contact angle α2 of the meshing (in comparison with α1 when this value is smaller than 0.7 shown in FIG. In addition, T in the figure
Reference numerals 1 and T2 respectively represent tangent lines of the tooth profile of the planetary gear 10 at the meshing portion.

As is apparent from FIG. 3, when the contact angle α2 is large, even if the radial deflection amount ΔB is the same, for example, this should not be significantly manifested as the circumferential deviation ΔC2. It is possible (ΔC1> ΔC
2). This effectively absorbs the influence of machining accuracy (mainly manifested as an eccentricity error or an error in the radial direction such as tooth groove runout) by the radial deflection of the inner tooth holding portion 276, and the same machining is performed. This means that even in the case of accuracy (deflection amount), the influence in the circumferential direction (which appears as pulsation, rotational irregularity, or error in rotational angle) can be further reduced.

Further, the large contact angle α2 means that the teeth are standing, so that ratcheting at the time of overload can be prevented.

Further, in this embodiment, the internal tooth holder 2 is
Reference numeral 76 denotes an internal tooth holding portion main body 278 and the internal tooth holding portion main body 2
The inner tooth holder 276 is made of a material harder than 78.
It is installed rotatably on the inner peripheral side of the
Since each roller pin 274 is configured with a plurality of roller pins 274 that form the inner teeth, each roller pin 274 that is long and hard in the axial direction can be obtained while obtaining a sufficient amount of bending (particularly, the amount of bending in the radial direction). Because it will make up the teeth,
It becomes possible to prevent the tooth profile itself from being distorted, and it is possible to reduce the influence of bending in the circumferential direction as much as possible.

In this embodiment, the thick portion 280 is formed only at one end of the inner tooth holding portion 276 on the side opposite to the flange side in the axial direction, but the thick portion forming method in the present invention is not limited to this. However, in the case where the number of planetary gears is three or more, for example, a plurality of planetary gears are formed in the axial direction in order to equalize the transmission torque that each planetary gear bears. Good. Also, the shape of formation is
In short, the amount of bending of the internal gear is equal to each planetary gear,
Further, the value is not particularly limited as long as the value is within a range capable of absorbing the processing error. It should be noted that this range is preferably 0.5 to 3 times the machining tolerance of the planetary gear.
It is 0 times, more preferably 1.5 times to 2.5 times.

Further, in the above-mentioned embodiment, an example in which the internal teeth are of the roller pin type has been 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 main body. It is naturally applicable to the type in which the internal teeth are directly formed.

[0058]

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 cross-sectional view of the main part near the internal gear of FIG.

FIG. 3 is a diagram showing the effects of comparing a small contact angle and a large contact angle with each other.

FIG. 4 is a vertical sectional view showing an example of a conventional speed reducer of this type.

FIG. 5 is a vertical sectional view showing another conventional example.

[Explanation of symbols]

40 ... bolt 214 ... reducer 218A, 218B ... Eccentric body 210 (210A, 210B) ... Planetary gear 230 ... Cross roller (bearing) 270 ... Internal gear 272 flange 274 ... Roller pin ... 276 ... Internal tooth holder 278 ... Main body of internal tooth holder 280 ... Thick part

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3J027 FA01 FB32 FC12 GA01 GB06                       GC02 GC22 GD04 GD08 GD12                       GE11                 3J030 AA02 AB04 BA01 BB06 CA10                 3J063 AA27 AB15 AC01 BA01 BA09                       CA01 CB05 CB17

Claims (6)

[Claims] 1. A planetary gear structure in which a planetary gear having external teeth internally contacts an internal gear having internal teeth, wherein the internal gear is supported by a bearing in a region on one axial side of the planetary gear. A flange part capable of holding the transmission torque of the internal gear, and a flexible internal part extending from the flange part in a cylindrical shape in a cantilever state in the axial direction and having the internal teeth on its inner circumference. A planetary gear structure, comprising: a tooth holding portion. 2. The planetary gear structure according to claim 1, wherein a thick-walled portion for increasing the rigidity near the portion is formed in a portion of the internal tooth holding portion in the axial direction. 3. The thickened portion according to claim 2, wherein a thickened portion is formed on an end portion of the inner tooth holding portion on the side opposite to the flange in the axial direction for increasing rigidity near the end portion on the side opposite to the flange. Characteristic planetary gear structure. 4. The internal tooth holding part according to claim 1, wherein the internal tooth holding part is formed of an internal tooth holding part main body and a material harder than the internal tooth holding part main body. A planetary gear structure, wherein the planetary gear structure is rotatably mounted on the inner peripheral side, and each roller pin is composed of a plurality of roller pins that form the inner teeth. 5. The planetary gear structure according to claim 1, wherein the planetary gear structure is an oscillating type planetary gear in which the planetary gear internally meshes with the internal gear while eccentrically oscillating. A swinging internally meshing type planet that outputs either the rotation corresponding to the rotation component of the planetary gear when the internal gear is fixed or the rotation of the internal gear when the rotation of the planetary gear is restricted. When the gear ratio is a gear structure and the speed ratio obtained by the planetary gear structure is i, the eccentricity of the planetary gear is e, and the pitch circle radius of the internal teeth of the internal gear is R, then (i + 1). A planetary gear structure, wherein each parameter is set so that e / R ≧ 0.7 holds. 6. The bending amount at rated output of a meshing portion of the internal gear holding portion of the planetary gear according to any one of claims 1 to 5, which is 0.5 of a machining tolerance of the planetary gear.
A planetary gear structure characterized by being set to double to 3.0 times.