JP2004301273A - Speed reducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a speed reducer easy and inexpensive in manufacture and installation, and reducing a backlash while realizing the high speed reduction ratio. <P>SOLUTION: This speed reducer G1 has two-stage speed reduction parts of a front stage speed reduction part 100 of an inscribed meshing planetary gear structure having external gears 130 and 132 and an internal gear 140 having a little tooth number difference, and a rear stage speed reduction part 200 of an inscribed meshing planetary gear structure having external gears 230 and 232 and an internal gear 240 having similarly a little tooth number difference, and receiving output of the front stage speed reduction part 100, and maintains the backlash of the rear stage speed reduction part 200 small in a level of 1/20 to 1/30 of the backlash of the front stage speed reduction part 100. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a speed reducer, and more particularly to a speed reducer used for driving and controlling a precision machine such as a joint drive device of an industrial robot or a precision machine tool.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a reducer having an internally meshing planetary gear structure including an external gear and an internal gear having a small difference in the number of teeth has been widely used in a joint drive device and a precision machine tool of an industrial robot.
[0003]
In this reduction gear, one of the external gears or the internal gear is eccentrically swung with respect to the other gear in a state where the rotation of one of the gears is restrained, and the rotation is restrained during the eccentric swing. The rotation component generated on the non-driven gear is taken out as an output, and a large reduction ratio can be obtained in one stage.
[0004]
By the way, in an application such as a robot arm in which forward and reverse rotations are repeated and it is required to reliably position the gear at a predetermined position, the existence of backlash of each gear becomes a problem. That is, there is an unavoidable backlash in the meshing of the gears. However, if the backlash is too large, there arises a problem that the positioning accuracy is lowered and the motion trajectory is disturbed. For this reason, reduction of this backlash has become a major issue in a speed reducer that drives and controls this kind of precision machine.
[0005]
As a device for eliminating such backlash in the internal meshing planetary gear structure, conventionally, for example, an external gear, an internal gear, etc. are divided into two for normal rotation and reverse rotation, or roles are divided for normal rotation and reverse rotation. Or other techniques have been proposed. In addition, the applicant has proposed a technique that focuses on a gap between an outer pin and an outer pin hole (see Patent Document 1).
[0006]
[Patent Document 1]
Japanese Patent Publication No. 5-86506
[Problems to be solved by the invention]
However, these prior arts have the demerits of halving the transmission capacity and increasing the manufacturing cost, although the respective effects can be obtained correspondingly, so that the best results are not necessarily obtained. Was not.
[0008]
Further, in recent years, there has been a situation in which the upper limit of the rotational speed of a servomotor as a drive source has been increased to about several times that of a conventional one, and thus a higher reduction ratio has been demanded of a speed reducer. . However, the higher the reduction ratio, the smaller the tooth-shaped module becomes, so the transmission capacity becomes smaller, and it is more difficult to form the tooth profile accurately and fit it accurately to fit in the controlled backlash. Tend to occur.
[0009]
The present invention has been made in order to solve such a conventional problem, and it is easy to manufacture and assemble at a low cost while maintaining a high reduction ratio, and the backlash is kept small. It is an object of the present invention to provide a speed reducer that can perform the operation.
[0010]
[Means for Solving the Problems]
The present invention includes a front-stage reduction portion of an internally meshing planetary gear structure including an external gear and an internal gear having a small difference in the number of teeth, and an external gear and an internal gear having a small difference in the number of teeth, And a rear-stage reduction unit having an internal meshing planetary gear structure that further reduces the speed in response to the output of the front-stage reduction unit. The front-stage reduction unit and the rear-stage reduction unit have the same processing for backlash. When manufactured under the control of accuracy, when the ratio of the backlash of the rear deceleration section to the backlash of the front deceleration section is smaller than α, the backlash of the rear deceleration section becomes (backlash of the front deceleration section × The above-mentioned problem has been solved by a configuration set to be smaller than α).
[0011]
Here, the "small difference in the number of teeth" refers to a difference in the number of teeth of about 1 to 6.
[0012]
In order to obtain a reduction gear having a low backlash, a low cost and a high reduction ratio at a low cost, the present invention is configured such that both the front reduction gear and the rear reduction gear have a two-stage reduction gear having an internally meshing planetary gear structure. Then, the backlash of the rear deceleration section is intentionally set to be smaller than the backlash of the front deceleration section.
[0013]
As a result, it is possible to obtain a speed reducer that is easy to manufacture and assemble as the whole speed reducer, is low in cost, and has low backlash, while realizing a high speed reduction ratio.
[0014]
Details such as the reason will be described later.
[0015]
Note that the ratio α is practically about 1/2 to 1/3. Therefore, if the backlash of the rear deceleration section is set to be smaller than 1/10 of the backlash of the front deceleration section, the effects intended by the present invention can be sufficiently enjoyed.
[0016]
Further, the difference in the number of teeth between the external gear and the internal gear of the preceding reduction unit may be set to two or more. As a result, it is possible to easily obtain the reduction ratio of the preceding reduction unit required to realize the total reduction ratio to be obtained in the present reduction gear, particularly, the reduction ratio in the region of about 1/6 to 1/30. become.
[0017]
Further, a mechanism for absorbing a relative oscillating component between the external gear and the internal gear in the post-stage reduction unit is provided with an eccentric amount between the external gear and the internal gear in a hole formed in the oscillating gear. The inner pin has a structure having an inner pin capable of absorbing a considerable deviation of the axis, and the inner pin has an eccentric protrusion corresponding to the amount of eccentricity on its outer periphery, and the inner pin has an eccentric protrusion. If the eccentric inner pin does not have a space corresponding to the amount of eccentricity between the pins, it is possible to effectively reduce the backlash of the post-stage reduction unit.
[0018]
Furthermore, if the front-stage speed reduction unit and the rear-stage speed reduction unit can be divided, the degree of freedom in design can be further increased.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0020]
1 is a sectional view showing a main part of a speed reducer according to an embodiment of the present invention, FIGS. 2 and 3 are sectional views taken along lines II-II and III-III in FIG. 1, and FIG. FIG. 5 is a cross-sectional view showing an example in which the machine is applied to drive a joint of an industrial robot.
[0021]
The speed reducer G1 is connected to a motor (servo motor) M, and is used as a part of a so-called geared motor. The speed reducer G1 is connected to the first arm 12 of the industrial robot 10 in a manner as shown in FIG. Attached to rotate arm 14.
[0022]
The reduction gear G <b> 1 includes a front-stage reduction unit 100 having an internal meshing planetary gear structure and a rear-stage reduction unit 200 receiving the output of the front-stage reduction gear unit 100.
[0023]
Hereinafter, the first-stage reduction unit 100 and the second-stage reduction unit 200 will be described in detail in this order.
[0024]
In FIG. 1, a first-stage speed reduction unit 100 is accommodated in a first-stage casing 102. The front casing 102 includes a main casing 104 and first and second side covers 106 and 108 connected to both sides in the axial direction. A connecting portion 112 is integrally extended at one end of the input shaft 110 of the front reduced side portion 100. An insertion hole 114 is formed in the connection portion 112, and the motor shaft 30 of the motor M is inserted and connected to the insertion hole 114.
[0025]
The input shaft 110 is supported by a first side cover 106 of the front casing 102 and a flange body 172 of a front output shaft 170 (= the rear input shaft 210) described later via a pair of bearings 120 and 122. An eccentric body 124 is incorporated between the pair of bearings 120 and 122. Two external gears 130 and 132 are mounted on the outer periphery of the eccentric body 124 via roller bearings 126 and 128 so as to be swingably rotatable. The external gears 130 and 132 are internally meshed with an internal gear 140 integrated with the casing main body 104 of the front casing 102. The internal teeth of the internal gear 140 are formed by roller-shaped pins (external pins) 142.
[0026]
Internal pin holes 150 and 152 are formed through the two external gears 130 and 132, respectively, and the internal pin 160 is inserted therein. A pipe-shaped inner roller 162 is rotatably mounted on the inner pin 160. The inner pin 160 is fixed to a flange body 172 formed integrally with the previous output shaft 170, and is supported by the flange body 172 in a cantilever state.
[0027]
The front-stage output shaft 170 is directly used as the rear-stage input shaft 210 of the rear-stage reduction unit 200.
[0028]
The latter reduction unit 200 is housed in the latter casing 202.
[0029]
The rear input shaft 210 is supported by first and second output flanges 266 and 268, which will be described later, via a pair of tapered roller bearings 222 and 220, and the flange body 172 is connected to a front casing via a ball bearing 190. It is also supported by the second side cover 108 of 102. An eccentric body 224 is incorporated between the pair of tapered roller bearings 220 and 222. Two external gears 230 and 232 are mounted on the outer periphery of the eccentric body 224 via roller bearings 226 and 228. The external gears 230 and 232 are internally meshed with an internal gear 240 integrated with the rear casing 202. The internal teeth of the internal gear 240 are formed by roller-shaped pins (outer pins) 242.
[0030]
Internal pin holes 250 and 252 are formed through the two external gears 230 and 232, respectively, and a highly accurate eccentric internal pin 260 is inserted therein. The eccentric inner pin 260 is different from the inner pin 160 of the preceding stage reduction portion 100 and is slidable on the entire outer circumference of the inner pin holes 250 and 252 via roller bearings 262 and 263 (corresponding to the eccentric amount). ) Eccentric projections 264 and 265 are provided, and there is no space corresponding to the amount of eccentricity between the inner pin holes 250 and 252.
[0031]
The eccentric inner pin 260 is supported at both ends by tapered roller bearings 270 and 272 on a pair of disk-shaped first and second output flanges 266 and 268 arranged on both sides of the external gears 230 and 232. ing.
[0032]
The first and second output flanges 266 and 268 are rotatably supported by the rear casing 202 via tapered roller bearings 274 and 276, respectively.
[0033]
The latter stage input shaft 210, the eccentric inner pin 260, and the first and second output flanges 266, 268 are supported by tapered roller bearings 220, 222, 270, 272, 274, 276. Is used for the purpose of driving the joints of the first arm 12 and the second arm 14 of the industrial robot 10, so that a load in the thrust direction is input from either of the first and second arms 12 and 14. This is because there is a possibility that
[0034]
Here, the connection mode of each member and the like will be described with reference to FIG.
[0035]
The first and second output flanges 266 and 268 of the rear reduction section 200 are firmly fixed by carrier pins 280. The first output flange 266 and the carrier pin 280 are fixed by bolts 282. On the other hand, the second output flange 268 and the carrier pin 280 are fixed by a bolt 286 inserted and screwed through the second arm 14.
[0036]
The casing 32 of the motor M and the first side cover 106 of the front reduction section 100 can be connected and separated by bolts 52 through spigots 50. Further, the second side cover 108 of the front reduction section 100 and the rear casing 202 of the rear reduction section 200 can also be connected and divided by bolts 55 through the spigot 54. Furthermore, the bolt position P1 of the second side cover 108 and the rear casing 202 matches the mounting hole position P2 of the first arm 12 of the industrial robot 10, and the connection of the second side cover 108 and the rear casing 202 Further, the cover 108 and the casing 202 are attached to the first arm 12 at the same time by the bolt 55.
[0037]
The outer diameter of the front deceleration section 100 is set smaller than the outer diameter of the rear deceleration section 200, and the space S1 secured thereby can accommodate accessories such as an encoder (not shown).
[0038]
As is clear from FIG. 2, the number of teeth of the external gears 130 and 132 of the pre-stage reduction unit 100 is “12”, the number of teeth of the internal gear 140 is “14”, and the difference in the number of teeth is “2”. The ratio is 2/12 = 1/6. As is clear from FIG. 3, the number of teeth of the external gears 230 and 232 of the rear-stage reduction unit 200 is “78”, the number of teeth of the internal gear 240 (the number of the outer pins 242) is “80”, and the number of teeth is The difference is “2”, and the reduction ratio is 2/78 = 1/39. Since it is necessary to manufacture the latter-stage reduction unit 200 precisely, including the management of backlash, it is desirable to set the reduction ratio to 1/50 or less.
[0039]
Here, the backlash will be described in detail.
[0040]
“Backlash” is a range in which the output shaft moves (rotates) with the input shaft of the speed reduction unit stopped, and the unit is “degree” or “minute”.
[0041]
In general, when the speed reducer is manufactured under the same level of manufacturing control, the backlash tends to be reduced as the reduction ratio increases and as the frame number (the concept of size or capacity) increases. For example, if the machining accuracy and the frame number are equal, the backlash A2 of the rear reduction unit 200 at the reduction ratio 1/39 is about ２〜 to の of the backlash A1 of the front reduction unit 100 having the reduction ratio of 1/6. Become smaller. This is because, in the combination of the reduction ratio and the frame number, when the former reduction gear and the latter reduction gear are manufactured under the control of the same processing accuracy with respect to the backlash, the backlash of the latter reduction gear is larger than the backlash of the former reduction gear. , Smaller ratio α ”(α = １ ／ to ３).
[0042]
In this embodiment, the backlash A2 is intentionally reduced to about 1/10 of the ratio α. That is, as a result, the rear-stage backlash A2 is set to be 1/20 to 1/30 of the front-stage backlash A1.
[0043]
In addition, as for the manufacturing technique itself for reducing the backlash, a known backlash reduction method can be adopted. For example, in the simplest case, several types of external gears having slightly different dimensions are prepared, and actually incorporated to determine the state of occurrence of backlash and the smoothness of rotation in the set of the external gear and the internal gear. A method of selecting an optimal external gear while confirming it may be used. Alternatively, as described above, for example, an external gear, an internal gear, or the like may be axially divided into two for normal rotation and for reverse rotation.
[0044]
Next, the operation of the speed reducer G1 according to this embodiment will be described.
[0045]
When the input shaft 110 of the pre-stage reduction unit 100 is rotated by the rotation of the motor M, the eccentric body 124 integrated with the input shaft 110 also rotates. When the eccentric body 124 rotates, the external gears 130 and 132 try to oscillate around the input shaft 110. However, since the internal gear 140 suppresses the rotation, the external gears 130 and 132 In this case, almost only swinging is performed while being in contact with the internal gear 140. However, since the number of teeth of the external gears 130 and 132 is set to 12 and the number of teeth of the internal gear 140 is set to 14, the external gears 130 and 132 become the internal gear 140 every one rotation of the input shaft 110. On the other hand, it shifts (rotates) by the difference in the number of teeth “2”. This means that one rotation of the input shaft 110 has been reduced to a rotation of −2/12 of the external gears 130 and 132, that is, a rotation of a reduction ratio of −1/6. A minus sign indicates that the rotation direction of the external gears 130 and 132 is opposite to the rotation direction of the input shaft 110. The rotation of the external gears 130, 132 is absorbed by the gap between the inner pin holes 150, 152 and the inner roller 162, and only the rotation component is passed through the inner pin 160 to the output shaft 170 (the input shaft 210). ).
[0046]
In the rear-stage deceleration unit 200, the same deceleration action as in the front-stage deceleration unit 100 is performed. That is, the external gears 230 and 232 are shifted (rotated) by the tooth number difference “2” with respect to the internal gear 240 every one rotation of the rear-stage input shaft 210. However, since the number of teeth of the external gears 230 and 232 of the rear-stage reduction unit 200 is set to 78 and the number of teeth of the internal gear 240 is set to 80, one rotation of the rear-stage input shaft 210 ends up being-of the external gear. The rotation is reduced to a rotation of 2/78, that is, a rotation of a reduction ratio of -1/39. Note that the rotation direction is once reversed in the first-stage reduction unit 100, but is reversed again in the second-stage reduction unit 200. Therefore, the external gears 230 and 232 of the second-stage reduction unit 200 are eventually rotated in the same direction as the rotation of the motor M. Will rotate.
[0047]
The rotation of the external gears 230 and 232 is absorbed by the presence of the eccentric projections 264 and 265 of the eccentric inner pin 260, and only the rotation component of the external gears 230 and 232 is transmitted to the external gears 230 and 232 through the eccentric inner pin 260. The power is transmitted to the first and second output flanges 266 and 268 arranged on both sides. Since the eccentric inner pin 260 has no space corresponding to the amount of eccentricity between the eccentric inner pin 260 and the inner circumferences of the inner pin holes 250 and 252, an increase in backlash here is prevented. Since the first and second output flanges 266 and 268 are firmly connected via the carrier pin 280, the two output flanges 266 and 268 rotate integrally, and the rotation of the output flanges 266 and 268 is performed by the industrial robot 10 which is a counterpart machine. The power is transmitted to the second arm 14 via a bolt 286 and a bolt connecting the second arm 14 and the output flange 266 (not shown) (see FIG. 4).
[0048]
As a result, a deceleration corresponding to a reduction ratio of (−1/6) × (−1/39) = 1/234 is realized by multiplication with the preceding-stage reduction unit 100.
[0049]
Here, the operation relating to the backlash in this embodiment will be described in more detail.
[0050]
The rear deceleration unit 200 is integrated with the second arm 14 of the industrial robot 10, and the magnitude of the backlash directly affects the control performance of the industrial robot 10 as it is. As described above, in the present embodiment, the post-stage deceleration unit 200 is manufactured under stricter conditions regarding backlash, such as by employing the eccentric inner pin 260, and as a result, the level is much lower than the ratio α, that is, Since about 1/20 to 1/30 of the backlash A1 of the front deceleration section 100 is ensured, good backlash characteristics can be enjoyed.
[0051]
This means that, when observed from a different viewpoint, the front deceleration section 100 can be designed and manufactured without strict requirements for the backlash A1, which means that cost reduction can be realized. Depending on the application, in some cases, a general-purpose deceleration unit may be used as it is.
[0052]
More specifically, for example, when the backlash A1 of the rear deceleration unit 200 is 0.3 minutes, the backlash A1 of the front deceleration unit is 20 to 30 times the backlash A1. 9 minutes is fine. At this level, the former reduction unit 100 can be manufactured at a much lower cost than the latter reduction unit 200. In consideration of the fact that the backlash A1 in the first-stage reduction unit 100 is compressed to one- (the denominator) of the reduction ratio of the second-stage reduction unit 200 at the stage of passing through the second-stage reduction unit 200, the final first , And the second output flanges 266 and 268 are set so as not to significantly affect the total backlash.
[0053]
In the above-described embodiment, the backlash A2 of the rear-stage deceleration unit 200 is reduced as compared with the front-stage deceleration unit 100 to a level that is much lower than the ratio α. However, in the present invention, both backlashes A1 and A2 are not necessarily used. There is no need to make a difference. As described above, in the case of equivalent processing accuracy, qualitatively, the ratio α tends to decrease as the reduction ratio increases and as the frame number increases. However, the relationship between the ratio α and the reduction ratio or the frame number is not always linear. Speaking of the reduction ratio, if it becomes higher than 1/20, it will not become so small thereafter. The same applies to the frame number.
[0054]
As a result, the influence of the reduction ratio and the frame number (the range in which the ratio α varies) is at most about 1/5. Accordingly, with respect to the back-stage backlash A2, the level is clearly lower than the ratio α, that is, the backlash A2 of the back-stage reduction unit 200 is reduced to 1/10 or less (more preferably 1/15 or less) of the backlash A1 of the front-stage reduction unit 100. If "intentionally small" is ensured, the predetermined effects of the present invention can be enjoyed accordingly.
[0055]
The description of the operation of the embodiment will be continued.
[0056]
Since the pre-stage reduction unit 100 is located on the upstream side in the power transmission path, each member including the input shaft 110 rotates or swings at high speed. However, since the backlash A1 is set relatively large, abundant lubricating oil can be secured between the members (particularly, between the tooth surfaces of the external gears 130 and 132 and the internal gear 140), and lubrication can be ensured. Properties and durability can be improved.
[0057]
Further, in this embodiment, since the reduction units 100 and 200 having the two-stage internally meshing planetary gear structure are provided, a high reduction ratio can be easily realized. That is, in the present embodiment, as the structure of the speed reduction unit, a lower-cost parallel shaft gear structure alone is not dared to be adopted by itself, but the internal reduction mesh planetary gear structure is adopted for both the speed reduction units 100 and 200. With this configuration, the following operation is obtained.
[0058]
That is, the motor (servo motor) M used as a drive source previously generally rotates at a rotation speed of about 1000 rpm to 2000 rpm, but in recent years, a servo motor close to 10,000 rpm at a higher speed from several thousand rpm. Has also appeared. Therefore, the total reduction ratio required for the speed reducer is higher, and more specifically, a total reduction ratio of about 150 to 400 is required. However, in the case of a reduction section having a parallel shaft gear structure, only a reduction ratio of about 1/5 can be practically obtained in one stage. Requires a high reduction ratio of about 1/30 to 1/80 by simple calculation.
[0059]
In the case where the rear-stage reduction portion has an internally meshing planetary gear structure, it is possible to sufficiently achieve the reduction ratio in this region. However, the reduction ratio region most easily produced is in the range of 1/30 to 1/40, which is not so wide. Absent. As described above, when the reduction ratio is increased to 1/20 or more, even if it is higher, the backlash does not become very small. Rather, it is not preferable to set such a high reduction ratio in terms of easiness of manufacturing, securing of transmission capacity, and above all, processing and assembling of precision parts with small backlash. In this sense, when it is desired to obtain a total reduction ratio of 180 or more, it is preferable to set the reduction ratio of the preceding reduction unit to 1/6 or more. However, it is unavoidable that the outer periphery of the front casing becomes large or that the front deceleration section must be provided in two steps.
[0060]
In the present embodiment, since the structure of the pre-stage reduction unit 100 is an internally meshing planetary gear structure, a reduction ratio of 1/6 or more can be easily realized. Since the outer circumference of the front casing 102 can be reduced, it is also possible to arrange a control device such as an encoder in an empty space.
[0061]
As a result, both the speed reduction units 100 and 200 can be configured as a speed reduction unit having a reduction ratio in an easy-to-manufacture region, and the design and manufacture of the latter-stage speed reduction unit 200 with particularly severe manufacturing conditions are facilitated. Note that the reduction ratio of 1/30 or less can be manufactured even if the number of teeth between the external gear and the internal gear is one, but the present embodiment sets the number of teeth to two or more. In addition, the present invention can be more easily realized with respect to a device having a small backlash.
[0062]
Furthermore, the reduction portion of the internally meshing planetary gear structure has a higher meshing ratio than the reduction portion of the parallel shaft gear structure, and therefore has less wear with time. This type of precision machine drive reducer, such as a reducer for a joint drive device of an industrial robot, is often operated continuously, and generally has a long operating time. Abrasion over time causes an increase in backlash. In the present embodiment, since both of the speed reducers 100 and 200 have an internally meshing planetary gear structure, good backlash characteristics can be obtained over a long period of time.
[0063]
Further, in the present embodiment, since the front reduction unit 100 and the rear reduction unit 200 and the front reduction unit 100 and the motor M can be respectively divided, there is a difference between the motor M and the rear reduction unit 100. Only the pre-stage deceleration unit 100 can be changed or replaced. For this reason, only one type of rear-stage reduction unit 200, which tends to be expensive due to high precision, is designed to have only one type, and one of the general-purpose internally meshing planetary gear structure reduction devices, which already have a wide variety of types, is connected to the front-stage reduction unit 100. By appropriately preparing the reduction gear, and incorporating it between the motor M and the rear reduction gear unit 200, a reduction gear with a small backlash having various reduction ratios can be easily obtained, and the degree of freedom in design can be increased. Can be.
[0064]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, while being able to implement | achieve a high reduction gear ratio, it is easy to manufacture and assemble, and it is low-cost and can obtain the reduction gear with small backlash.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a main part of a speed reducer according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a sectional view showing an example in which the speed reducer is applied to a joint part of an industrial robot.
DESCRIPTION OF SYMBOLS 10 ... Industrial robot 12 ... 1st arm 14 ... 2nd arm 100 ... Front reduction part 102 ... Front casing 106 ... 1st side cover 108 ... 2nd side cover 110 ... Input shaft 124 ... Eccentric bodies 130 and 132 ... External teeth Gear 140 ... internal gear 160 ... internal pin 170 ... front stage output shaft 200 ... rear stage reduction unit 202 ... rear stage casing 210 ... rear stage input shaft 230, 232 ... external gear 240 ... internal gear 260 ... eccentric internal pin 262, 264 ... First and second output flanges

Claims (6)

A front reduction unit having an internal meshing planetary gear structure having an external gear and an internal gear having a small difference in the number of teeth, and the external reduction gear having an external gear and an internal gear having a small difference in the number of teeth; And a two-stage speed reducer for the internal meshing planetary gear structure that receives the output of
When the former-stage decelerating unit and the latter-stage decelerating unit are manufactured under the control of the same processing accuracy with respect to the backlash, when the backlash of the latter-stage decelerating unit is smaller than the backlash of the former-stage decelerating unit, α A backlash of the rear speed reducer is set to be smaller than (backlash of the front speed reducer × α). In claim 1,
The backlash of the rear-stage reduction unit is set to be smaller than 1/10 of the backlash of the front-stage reduction unit. In claim 1 or 2,
The reduction gear wherein the difference in the number of teeth between the external gear and the internal gear of the front reduction unit is set to two or more. In claims 1 to 3,
A reduction gear wherein the reduction ratio of the preceding reduction unit is set to 1/6 or more. In any one of claims 1 to 4,
A mechanism for absorbing a relative oscillating component between the external gear and the internal gear in the rear reduction unit is provided by an amount corresponding to an eccentric amount of the external gear and the internal gear in a hole formed in the oscillating gear. It has a structure with an inner pin that can absorb the deviation of the axis of
The internal pin has an eccentric protrusion corresponding to the amount of eccentricity on its outer periphery, and is an eccentric inner pin having no space corresponding to the amount of eccentricity with the inner periphery of the hole. Machine. In any one of claims 1 to 5,
A reduction gear, wherein the front reduction section and the rear reduction section can be divided.

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