JP2004293682A - Drive mechanism with oscillating speed reduction part of inscribed engagement planetary gear structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To lower the noise of the whole unit much more by the original effect that can be obtained to the utmost by arranging a helical gear set. <P>SOLUTION: A helical gear set H1 having a helical pinion 30 and a helical gear 32 is provided with the front stage of the oscillating speed reduction part G1 of an inscribed engagement planetary gear structure. And the thrust reaction force applied member (the first bearing) 50 receiving the thrust load that occurs in the helical gear set H1 is arranged on the helical gear set side (more closer to the side of a motor 12 than the protrusion part 41 of an input shaft 40 in this case) in the axial direction of the above gear (an external teeth gear 46) that is oscillated eccentrically for the oscillating speed reduction part G1 of the above inscribed engagement planetary gear structure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a drive device having a swing speed reducer having an internally meshing planetary gear structure.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in the fields of a joint drive device of an industrial robot, a drive device of a conveyor, and the like, a drive device having a rocking reduction unit having an internally meshing planetary gear structure has been widely used.
[0003]
The swing reduction unit of the internal meshing planetary gear structure includes an external gear and an internal gear having a small difference in the number of teeth, and any one of the external gears or the internal gears in a state where the rotation of one of the gears is restricted. This gear eccentrically oscillates with respect to the counterpart gear, and the rotation component generated on the unconstrained gear at the time of this eccentric oscillation is taken out as an output. The ratio is obtained.
[0004]
An example of this type of driving device GM having a swing reduction portion G of an internally meshing planetary gear structure is disclosed in, for example, Japanese Patent Application Laid-Open No. 6-241282 (Patent Document 1).
[0005]
This structure is shown in FIG.
[0006]
A helical gear set H having a helical pinion 154 and a helical gear 155 cut directly to a motor shaft 153 is disposed at a stage preceding the swing reduction portion G. The helical gear set H is disposed as the preceding transmission mechanism because it is intended to obtain a higher reduction ratio with lower noise.
[0007]
The end of the casing 112 covering the swing reduction portion G is extended as it is, and also serves as a casing that covers the helical gear set H, and also serves as an end cover of the motor 160. That is, the motor 160 is a dedicated motor without an end cover, and by connecting the casing 112 and the cylindrical motor casing 161, the connection between the motor 160 and the speed reducer is performed. In this example, the end of the casing 112 and the end of the motor casing 161 are fitted with the spigot 163, and then fixed with the set screw 170.
[0008]
The operation of the driving device GM will be briefly described together with the description of the configuration. The rotation of the motor shaft 153 directly turns the rotation of the helical pinion 154, and the helical gear 155 meshing with the rotation rotates. As a result, first-stage deceleration is performed. The rotation of the helical gear 155 causes the rotation of the input shaft 151 of the oscillating reduction unit G of the internal meshing planetary gear structure, and the external gears 105a and 105b oscillate with the rotation of the input shaft 151 via the eccentric bodies 157a and 157b. Rotate dynamically. As a result, the external gears 105a and 105b rotate slowly while swinging due to the engagement between the external pins 111 corresponding to the internal teeth of the internal gear 110 and the external gears 105a and 105b.
[0009]
The movement of the external gears 105a and 105b is caused by the fact that the swing component is absorbed by the gap between the inner pin holes 119a and 119b and the inner pin 107, and only the rotation component is transmitted through the inner pin 107 to the flange portion of the output shaft 102. It is transmitted to 114 and the support ring 117. The torque transmitted to the support ring 117 is transmitted to the output shaft 102 via the carrier pin 116.
[0010]
The thrust load generated on the input shaft 151 by the meshing of the helical gear set H is transmitted to the flange 114 and the support ring 117 via a pair of bearings 172 and 174 supporting the input shaft 151 with the eccentric members 157a and 157b interposed therebetween. Has been taken by
[0011]
[Patent Document 1]
JP-A-6-241282
[Problems to be solved by the invention]
However, in the drive device according to this conventional example, the helical gear set is arranged in spite of the intentional arrangement of the helical gear set (instead of the normal spur gear set) in order to reduce noise. As a result, not only can noise not be reduced to the extent achievable on average, but also the overall noise can be rather high depending on the structure of the oscillating reduction section of the internal meshing planetary gear structure. was there.
[0013]
The present invention has been made in view of the above problems, and has been made based on the knowledge obtained as a result of a large number of prototypes and experiments, and aims to maximize the original noise reduction effect by disposing a helical gear set. It is an object of the present invention to provide a drive device capable of further reducing the noise of the entire device.
[0014]
[Means for Solving the Problems]
The present invention includes an external gear and an internal gear having a small difference in the number of teeth, and has a rocking reduction section of an internally meshing planetary gear structure for eccentrically rocking either the external gear or the internal gear. In the driving device, a helical gear is provided in a stage preceding the oscillating reduction unit, the oscillating reduction unit includes an input shaft that receives rotation of the helical gear, and a thrust reaction force applying member that receives a thrust load generated in the helical gear. However, the above problem is solved by a configuration in which the eccentrically oscillating gear of the oscillating reduction portion of the input shaft is arranged only on the helical gear side in the axial direction.
[0015]
Here, the "small difference in the number of teeth" means a difference in the number of teeth of about 1 to 6.
[0016]
The inventor carefully examined the conventional structure in which noise reduction could not be achieved despite the arrangement of the helical gear, and as a result, the input mesh planetary gear by the input shaft in the state where the thrust load generated in the helical gear was still applied. The fact that the external gear of the oscillating deceleration part of the structure was oscillating was found to be the cause.
[0017]
In general, even if a thrust load is generated on a specific shaft due to meshing in a helical gear set, if no other moment is applied to the shaft, a reaction force may be applied at any position of the shaft, thereby resulting in a particularly different effect. Does not occur. However, in the swing reduction portion of the internal meshing planetary gear structure, due to its structure, a radial moment rotating and moving in the circumferential direction is constantly applied to the shaft (input shaft). When a thrust load is applied to the input shaft in a state where a radial moment is generated, both moments are combined, and an eccentric body that should not give a reaction force to the thrust load partially It will function as a giving member. This means that an oblique force that rotates periodically is applied to the eccentric body.
[0018]
In particular, when the start / stop of the motor is repeated (especially, forward rotation and reverse rotation), or the acceleration and deceleration is repeated (especially, the rotation speed is increased / decreased by inverter driving or the like), the moment in the oblique direction is reduced. Since the angle and the size change, a very complicated oblique force acts on the eccentric body.
[0019]
In the drive device having the conventional helical gear set, the inherent noise reduction effect of the helical gear set could not be obtained because the complicated oscillating force applied to the eccentric body hindered the smooth swing rotation of the external gear. Inferred.
[0020]
Therefore, in the present invention, the thrust load generated by the meshing of the helical gear set is cut off on the helical gear side in the axial direction of the eccentrically oscillating gear on the shaft, and the thrust load of the oscillating reduction unit, particularly the oscillating gear, is It is intended to have no effect.
[0021]
As a result, the oscillating reduction portion of the internal meshing planetary gear structure is completely released from the thrust load generated by the helical gear, and can perform the original smooth oscillating rotation. As a result, the helical gear disposed at the front stage portion The set also became able to perform its original silent operation.
[0022]
In the present invention, the specific structure of the thrust reaction force applying member is not particularly limited. As the thrust reaction force applying member, the input shaft is rotatably supported, and the movement of the input shaft is controlled. By incorporating a bearing that restrains in any axial direction, the effects of the present invention can be enjoyed with a simple configuration.
[0023]
In addition, when a bearing having such a configuration is incorporated, even if the shaft that generates a thrust load becomes the input shaft of the swing reduction portion of the internal meshing planetary gear structure, no particular problem occurs. A configuration in which the input shaft is supported by the bearing and the bearing disposed on the side opposite to the helical gear in the axial direction of the eccentrically oscillating gear can be adopted without any trouble. As a result, the present invention can be implemented without increasing the number of parts, and the input shaft can be stably supported.
[0024]
A through-hole through which the helical pinion can be inserted from the outside of the casing cover is formed in a casing cover that covers one end in the axial direction of the swing reduction portion, and the helical gear and the helical gear inserted from outside are formed in the casing cover. In the case of adopting a configuration capable of meshing with the pinion, the meshing of the helical gear set is completed simultaneously with the connection of the motor, so that the assembly is easy.
[0025]
In this case, if a mounting hole in which a motor can be mounted is formed in the casing cover, a motor equipped with a commercially available helical pinion can be used. become able to.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0027]
FIG. 1 is a cross-sectional view showing a driving device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II of FIG.
[0028]
In the drive device 10, a motor 12 that is independent (existing as a single unit) of a casing 12A as a drive source and a speed reducer 14 having an oscillating speed reduction portion G1 of an internal meshing planetary gear structure are integrated. .
[0029]
The casing 16 of the speed reducer 14 includes a main body casing 18 and first and second end covers 20 and 22 arranged on both sides in the axial direction, and is integrated by bolts 24. The first end cover 20 on the side of the motor 12 has a mounting hole 26 through which the independent motor 12 can be mounted. The motor 12 is attached to the first end cover 20 by mounting bolts 28 penetrating the motor casing 12A. Can be connected to
[0030]
Helical pinion 30 is formed directly on motor shaft 13 of motor 12. The first end cover 20 is formed with a through hole 31 into which the helical pinion 30 is inserted. When the first end cover 20 and the casing 30 of the motor 12 are connected via the mounting hole 26, The helical pinion 30 is configured to face the inside of the first end cover 20.
[0031]
The oscillating reduction portion G1 of the internally meshing planetary gear structure accommodated in the casing 16 of the reduction gear 14 mainly includes the input shaft 40, the helical gear 32 incorporated in the input shaft 40, and the input shaft 40. An eccentric body 42 incorporated and rotating integrally with the input shaft 40, an external gear 46 mounted on the eccentric body 42 via a roller bearing 44 and capable of eccentric swinging around the input shaft 40, An internal gear 48 integrated with the main body casing 18 and in which the external gear 46 meshes internally.
[0032]
The input shaft 40 is supported by the first end cover 20 and the flange 58 of the output shaft 56 by a pair of first and second bearings 50 and 55. Among them, the first bearing 50 on the helical pinion 30 side (motor 12 side) corresponds to a thrust reaction force applying member in the present invention (detailed later). The first bearing 50 is a so-called ball bearing including a ball 53 between the inner ring 51 and the outer ring 52.
[0033]
The input shaft 40 extends from the first bearing 50 to the motor 12 side in a cantilever state, and a helical gear 32 that meshes with the helical pinion 30 to form the helical gear set H1 is mounted on the extending portion. ing.
[0034]
On the other hand, the output shaft 56 is connected to the second end cover via a bearing 60 provided near the flange 58 of the output shaft 56 and a large bearing 62 disposed near the tip of the second end cover 22. 22.
[0035]
As shown in FIG. 2, trochoid-shaped external teeth are formed on the outer periphery of the external gear 46, and the internal teeth of the internal gear 48 are rotated by a pin 49 rotatably incorporated in an arc-shaped groove. It is configured. The number of teeth of the external gear 46 is one less (in this embodiment) than the number of teeth of the internal gear 48 (a slight difference in the number of teeth). A through hole 47 is formed in the external gear 46, and an inner pin 72 covered with an inner roller 70 for promoting sliding fits loosely. The inner pin 72 is fixed to the flange portion 58 which is integrally expanded from the output shaft 56.
[0036]
Here, the first bearing 50 has an outer ring 52, one end of which is in contact with the stepped portion 21 of the first end cover 20, and the other end of which is incorporated in the same first end cover 20. It is in contact with 78. Therefore, the movement of the first bearing 50 in the axial direction with respect to the first end cover 20 is also restricted. Further, the inner ring 51 of the first bearing, together with the spacer 74 and the helical gear 32, is held between the projection 41 formed on the input shaft 40 and the retaining ring 76. Therefore, the first bearing 50 is incorporated in a manner that restricts the input shaft 40 from moving in the axial direction with respect to the first end cover 20 via itself. The thrust load of the input shaft 40 is received only by the first bearing 50.
[0037]
Next, the operation of the speed reducer 14 according to this embodiment will be described.
[0038]
When the motor shaft 13 of the motor 12 rotates, the helical pinion 30 formed at the tip of the motor shaft 13 rotates. As a result, the helical gear 32 meshing with the helical pinion 30 rotates, and the input shaft 40 of the swing reduction unit G1 of the internally meshing planetary gear structure rotates. When the input shaft 40 rotates, the eccentric body 42 integrated with the input shaft 40 also rotates. The external gear 46 attempts to oscillate around the input shaft 40 by the rotation of the eccentric body 42, but its rotation is suppressed by the internal gear 48 integrated with the main body casing 18. Reference numeral 46 performs almost only swing while inscribed in the internal gear 48.
[0039]
However, since the number of teeth of the external gear 46 is one less than the number of teeth of the internal gear 48, the external gear 46 has a tooth number difference “1” with respect to the internal gear 48 every one rotation of the input shaft 40. It will shift (rotate). This means that one rotation of the input shaft 40 has been reduced to -1 / (the number of teeth of the external gear 46) rotation of the external gear 46. A minus sign indicates that the rotation direction of the external gear is opposite to the rotation direction of the input shaft. The swing component of the external gear 46 is absorbed by the gap between the through hole 47 and the inner roller 70, and only the rotation component is transmitted to the output shaft 56 via the inner pin 72.
[0040]
Here, the thrust load generated when the helical pinion 30 and the helical gear 32 mesh with each other will be described. When the helical pinion 30 and the helical gear 32 mesh with each other, thrust loads are generated on the motor shaft 13 and the input shaft 40 on which the helical pinion 30 and the helical gear 32 are mounted, respectively, in opposite directions.
[0041]
Considering the thrust load generated on the input shaft 40, the direction in which the thrust load is generated depends on the rotation direction of the motor 12, but the thrust load may be generated in any direction. All of them are received via 50. That is, when a thrust load for urging the input shaft 40 toward the motor 12 is generated, the protrusion 41 of the input shaft 40, → the inner ring 51 of the first bearing 50, → the ball 53 of the first bearing 50, → It follows the path of the outer ring 52 of the one bearing 50, → the path of the step portion 21 of the first end cover 20, and is finally received by the first end cover 20. Further, when a thrust load for urging the input shaft 40 toward the non-motor side is generated, the retaining ring 76, the helical gear 32, the spacer 74, the inner ring 51 of the first bearing 50, and the ball of the first bearing 50 53, → the outer ring 52 of the first bearing 50, → follows the path of the retaining ring 78 of the first end cover 20, and is finally received by the first end cover 20 as well.
[0042]
This means that no matter what direction the thrust load generated at the end of the input shaft 40 due to meshing of the helical gear set H1 is generated, the internal stress is offset up to the first bearing 50. Means that That is, only the portion of the input shaft 40 that is interposed between the helical gear 32 and the first bearing 50 repeats compression / extension due to the application or release of the thrust load. (Left side of the figure), the unloaded state is maintained.
[0043]
Therefore, even if a radial load is applied to the eccentric body 42 due to the eccentric swing of the external gear 40, the radial load is prevented from interfering with the thrust load generated by the helical gear set H1. The moment in the oblique direction that tilts the shaft center does not occur. Therefore, the swing reduction portion G1 of the internal meshing planetary gear structure can swing or rotate while maintaining the original smoothness, and low noise can be maintained. As a result, the noise reduction of the entire device can be realized as it is because the noise reduction inherent in the helical is realized in the helical gear set H1.
[0044]
In this embodiment, the first end cover 20 is formed with a through hole 31 through which the helical pinion 30 can be inserted from the outside of the first end cover 20 (right side in the figure), and exists as a single body. A mounting hole 26 to which an independent motor 12 can be attached is formed, and the (independent) motor 12 can be attached to the first end cover 20 through the mounting hole 26, so that the above noise can be reduced. , Very easily and at low cost.
[0045]
In the above embodiment, the first bearing (ball bearing) 50 whose axial movement is restricted with respect to both the input shaft 40 and the first end cover 20 is incorporated as the thrust reaction force applying member. In the present invention, however, the point is that the thrust load generated on the input shaft is entirely received on the axial helical gear side of the eccentrically oscillating gear in the oscillating reduction portion of the internal meshing planetary gear structure. It is not always necessary to be a “ball bearing”, and in some cases, it is not necessary to be a “bearing”.
[0046]
Further, it is not always necessary to receive a thrust load in both directions by only one member. For example, a pair of thrust bearings is incorporated in a pair, and each of the members carries a thrust load in one of the directions. You may. However, even in this case, both of the pair of thrust bearings need to be present on the axial helical gear set side of the eccentrically oscillating gear.
[0047]
【The invention's effect】
According to the present invention, when a helical gear set is disposed in front of a swing reduction portion of an internal meshing planetary gear structure, an adverse effect caused by the helical gear set is eliminated, and the original noise reduction effect of the helical gear set is ensured. An excellent effect of being able to be drawn out is obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a drive device having an oscillating reduction section of an internally meshing planetary gear structure according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line II-II of FIG. Sectional view showing an example of a drive device having a rocking reduction section of the internal meshing planetary gear structure of FIG.
G1: Oscillating reduction unit H1 ... Helical gear set 10 ... Drive device 12 ... Motor 13 ... Motor shaft 14 ... Reduction gear 16 ... Casing 18 ... Main body casing 20 ... First end cover 21 ... Step 22 ... Second end cover 24 Bolt 26 Mounting hole 30 Helical pinion 32 Helical gear 40 Input shaft 41 Projection 42 Eccentric body 46 External gear 48 Internal gear 50 First bearing 51 Inner ring 52 of first bearing Outer ring 53 of the first bearing 53 Ball of the first bearing 55 Second bearing 56 Output shafts 76 and 78 Retaining ring

Claims (5)

A drive device comprising an external gear and an internal gear having a small difference in the number of teeth, and having a rocking reduction section of an internal meshing planetary gear structure for eccentrically rocking either the external gear or the internal gear,
A helical gear is provided in front of the oscillating reduction unit, and the oscillating reduction unit includes an input shaft that receives rotation of the helical gear, and
A thrust reaction force applying member for receiving a thrust load generated in the helical gear is disposed only on an axial helical gear side of an eccentrically oscillating gear of the oscillating reduction portion of the input shaft. A drive device having an oscillating reduction unit having a planetary gear structure. In claim 1,
The thrust reaction force applying member,
A bearing for rotatably supporting the input shaft and restricting the movement of the input shaft in any axial direction. Drive. In claim 2,
A drive device having a rocking reduction section of an internally meshing planetary gear structure, wherein the input shaft is supported by the bearing and a bearing disposed on the side of the eccentrically rocking gear opposite to the helical gear in the axial direction. In any one of claims 1 to 3,
A through hole is formed in an end cover that covers one end in the axial direction of the swing deceleration unit, through which a helical pinion can be inserted from outside the end cover,
A drive device having a swing reduction section of an internally meshing planetary gear structure, wherein meshing between the helical gear and a helical pinion inserted from the outside is enabled in the end cover. In claim 4, further comprising a motor with a helical pinion as a drive source,
The helical gear is supported by a casing on the side of the swing reduction unit,
The helical pinion and the helical gear mesh with each other by connecting the casing on the side of the swing reduction unit and the casing of the motor via a mounting hole formed in the end cover. A drive device having a swing reduction portion having an internal meshing planetary gear structure.

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