JP2024013353A - Planetary gear device - Google Patents

Abstract

To provide a planetary gear device capable of suppressing backlash even in a small size.SOLUTION: A planetary gear device comprises: a tapered sun gear; a tapered planetary gear that meshes with the sun gear; an internal gear that meshes with the planetary gear; and a carrier including a carrier pin that rotatably supports the planetary gear. The carrier pin is made of a flexible material and constitutes the planetary gear device. With this configuration, it is possible to maintain a state in which tooth surfaces of the sun gear and tooth surfaces of the planetary gear are in contact with each other by a preload by the carrier pin without providing a separate preload mechanism.SELECTED DRAWING: Figure 1

Description

The present invention relates to a planetary gear system.

2. Description of the Related Art Conventionally, a planetary gear device is known that has a structure in which backlash is reduced by applying preload to a gear using a spring or the like. For example, Patent Document 1 discloses a planetary gear device in which a sun gear, a planetary gear, and an internal gear that mesh with each other are made into a tapered shape, and backlash is removed by applying preload to the planetary gear in the axial direction with a spring. ing.

Japanese Patent Application Publication No. 5-39824

For example, when it comes to a small planetary gear device with an outer diameter of φ20 mm or less, it is difficult to apply a preload mechanism as disclosed in Patent Document 1.
In order to incorporate a preload mechanism for reducing backlash into such a small-sized planetary gear device, some ingenuity is required.
SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a planetary gear device that can reduce backlash even if it is small in size.

One means for solving the above problem is to provide a planetary gear device with a tapered sun gear, a tapered planetary gear that meshes with the sun gear, an internal gear that meshes with the planetary gear, and a planetary gear that is rotatably supported. The device includes a carrier including a carrier pin, and the carrier pin is made of a flexible material.

According to the present invention, it is possible to provide a planetary gear device that can suppress backlash even in a small size.

1 is a longitudinal cross-sectional view showing an example of a planetary gear device according to the present invention. 2 is a sectional view taken along the line (A)-(A) in FIG. 1. FIG. FIG. 2 is a perspective view showing the structure of the planetary gear device. It is a schematic diagram explaining the state before each gear meshes in the same planetary gear apparatus. It is a schematic diagram explaining the state when each gear meshes in the same planetary gear apparatus. It is a longitudinal cross-sectional view showing another example of the planetary gear device according to the present invention. 7 is a sectional view taken along the line (B)-(B) in FIG. 6. FIG.

One of the features of this embodiment is that the planetary gear device includes a tapered sun gear, a tapered planetary gear that meshes with the sun gear, an internal gear that meshes with the planetary gear, and a planetary gear that is rotatably supported. The present invention includes a carrier including a carrier pin, and the carrier pin is made of a flexible material.
According to this configuration, since the carrier pin itself becomes a main part of the preload mechanism without providing a separate preload mechanism, it is possible to maintain a state in which the tooth surface of the sun gear and the tooth surface of the planetary gear are in contact with each other. Therefore, backlash can be suppressed even in a planetary gear device of such a small size that it has been difficult to reduce backlash.

In addition to the above characteristics, the taper of the sun gear widens in one direction in the axial direction, while the taper of the planetary gear extends in the opposite direction to the taper of the sun gear. This is because the planetary gears are arranged so that they spread out.
According to this configuration, when placing the sun gear at a predetermined position in the axial direction, the sun gear can be moved in the axial direction while aligning the tooth surfaces of the sun gear and the planetary gear, making it easy to adjust the position. Become.

Another feature, in addition to the above features, is that, as a more specific aspect, the module values of the sun gear, planetary gear, and internal gear are set to 0.04 to 0.3. The planetary gear device of this embodiment can also be applied to a small planetary gear device with an outer diameter of φ20 mm or less, in which it is difficult to incorporate a preload mechanism for reducing backlash. When this applicable size range is expressed by each gear module, it corresponds to a range of approximately 0.04 to 0.3.
According to this configuration, the planetary gear device can suppress backlash even though it is ultra-small in size, so it is possible to downsize the entire unit device that suppresses backlash.

In addition to the above features, other features include the following configuration of the planetary gear device. First, the first planetary gear mechanism consists of the above-mentioned sun gear, planetary gears, internal gears, and a carrier including a carrier pin, and the first planetary gear mechanism is located on the input side coaxially with the first planetary gear mechanism located on the output side. and a second planetary gear mechanism. The second planetary gear mechanism includes a second sun gear, a second planetary gear, a second internal gear, and a second carrier including a second carrier pin. For one second internal gear, there are a plurality of second sun gears, second planetary gears, and second carriers, and the number of stages is determined by the number of second carriers.
According to this configuration, the first planetary gear mechanism on the output side suppresses backlash, while the second planetary gear mechanism significantly decelerates the input rotation, so the thrust load generated to suppress backlash is reduced. It becomes easier to prevent the signal from being transmitted to the input side and causing a decrease in mechanism efficiency.

Other features include, in addition to the above features, the first planetary gear mechanism and the second planetary gear mechanism are connected by a connecting member, and the axial position of the sun gear of the first planetary gear mechanism is determined by this connecting member. It's because I did it.
According to this configuration, the axial position of the sun gear can be fixed at a position where the backlash between the sun gear and the planetary gears in the first planetary gear mechanism is "zero", and this state can be maintained.

Other features include, in addition to the above features, the sun gear of the first planetary gear mechanism is integrally fixed to the second carrier at the final stage on the output side among the multiple stages of the second carrier of the second planetary gear mechanism. Furthermore, the first planetary gear mechanism and the second planetary gear mechanism are coaxially connected by a connecting member.
According to this configuration, it is possible to provide a planetary gear device that is small and slender and can suppress backlash while suppressing an increase in the number of parts.

Hereinafter, particularly preferred embodiments of the above embodiment will be described in detail based on the drawings. In the following explanation, "axial direction" refers to the direction that is the center line of rotational movement when the output shaft, carrier, etc. in the planetary gear device rotates (for example, the vertical direction in FIG. 1). ing.

First, the basic structure of the planetary gear device 1 in this embodiment will be explained using FIGS. 1 to 3.
1 to 3 show the internal structure of the planetary gear device 1 in this embodiment.
FIG. 1 is a longitudinal sectional view of the planetary gear device 1. FIG.
FIG. 2 is a sectional view taken along the line (A)-(A) in FIG.
FIG. 3 is a perspective view of the planetary gear device 1, partially in section in order to explain the internal structure, and with some of the plurality of parts omitted.

The outer appearance of the planetary gear device 1 shows the gear housing 30, flange 50, output shaft 42a, etc. A planetary gear mechanism 100 including a sun gear 10, a planetary gear 20, an internal gear 31, a carrier 40, etc. is provided inside the gear housing 30.

The sun gear 10 is attached to the rotation shaft 3a of the input device 3 for the planetary gear system 1. Further, the tooth portion 10a of the sun gear 10 has a tapered shape that is inclined toward the axial direction. Note that the input device 3 can be, for example, an electric motor.

There are five planetary gears 20, and they are arranged so as to surround the sun gear 10 at equal intervals (see FIG. 2). The tooth portion 20a of the planetary gear 20 has a tapered shape that is inclined in the opposite direction to the sun gear 10 toward the axial direction. That is, the planetary gear 20 is disposed in such a direction that it expands in a direction substantially opposite to the taper expansion of the sun gear 10 . Each planetary gear 20 and the sun gear 10 mesh with each other.

The internal gear 31 is integrally formed inside the cylindrical gear housing 30. Five planetary gears 20 are positioned at equal intervals inside the internal gear 31 (see FIG. 2). Each of the planetary gears 20 and the internal gear 31 are in mesh with each other.

The carrier 40 integrally includes a carrier pin 41 and an output carrier 42. The output carrier 42 is formed with an output shaft 42a and a disk portion 42c. The disc portion 42c has a plurality of fixing holes 42h. A carrier pin 41 is inserted and fixed into this fixing hole 42h. The carrier pin 41 and the output shaft portion 42a are in a state in which they protrude in opposite directions in the axial direction with the disk portion 42c sandwiched therebetween.

The number of carrier pins 41 is the same as that of the planetary gears 20. Each carrier pin 41 rotatably supports each planetary gear 20 via a sleeve 43. The axial position of the planetary gear 20 on the carrier pin 41 is determined by the collar portion 43a of the sleeve 43. Further, the carrier pin 41 is made of a flexible material. Here, flexibility includes elasticity and superelasticity, and various alloys having these characteristics can be applied. Note that the sleeve 43 may be omitted by forming the carrier pin 41 into a stepped shape.

The flange 50 is fixed integrally with the gear housing 30. Further, the flange 50 holds a bearing 51 and a bearing 52. The output shaft 42a is rotatably supported by the bearings 51 and 52.

With the structure described above, when a rotation input is received from the input device 3, the rotation is transmitted to each planetary gear 20 via the sun gear 10. The planetary gear 20 rotates and revolves while meshing with the sun gear 10 and the internal gear 31. Finally, the revolution of the planetary gear 20 becomes the rotation of the output shaft 42a via the carrier 40.

Next, the meshing state of the sun gear 10, planet gear 20, and internal gear 31 in this embodiment will be explained in detail using FIGS. 4 and 5 in addition to FIGS. 1 to 3.
FIG. 4 is a schematic diagram illustrating a state before each gear is engaged.
FIG. 5 is a schematic diagram illustrating a state when each gear is meshed.

FIG. 4 shows a state in which the sun gear 10 is not placed at a predetermined position in the axial direction. That is, the input device 3 is not connected to the planetary gear device 1. At this time, not only the sun gear 10 and the planetary gear 20 are not meshed with each other, but also the planetary gear 20 and the internal gear 31 are not meshed as gears.

If the slope angle of the tapered portion of the tapered planetary gear 20 is α, then the slope angle of the taper portion of the similarly tapered sun gear 10 is doubled to 2α. Further, the direction of the taper, which widens outward or narrows inward along the axial direction, is opposite between the sun gear 10 and the planetary gear 20.
On the other hand, the internal gear 31 is not tapered. Therefore, the angle between the axial teeth of the internal gear 31 and the slope of the tapered portion of the planetary gear 20 in the non-meshing state shown in FIG. 4 is α.

FIG. 5 shows a state in which the sun gear 10 is arranged at a predetermined position in the axial direction. That is, the input device 3 is connected to the planetary gear device 1. At this time, the sun gear 10 and the planetary gear 20, and the planetary gear 20 and the internal gear 31 mesh as gears.

When the sun gear 10 is placed at a predetermined position in the axial direction, the slope of the planet gear 20 is equal to that of the internal gear 31 because the carrier pin 41 supporting the planet gear 20 is made of a flexible material. It is in a state where it is tilted down at an angle α. Therefore, as shown in FIG. 5, when the sun gear 10 is in a predetermined position and the gears are in mesh with each other, the angle between the axial teeth of the internal gear 31 and the slope of the tapered portion of the planetary gear 20 is It is 0°.

Further, when the gears are in mesh with each other at this predetermined position, a preload can be applied to the sun gear 10 and the planet gear 20 because the carrier pin 41 is flexible. As a result, the backlash between the sun gear 10 and the planetary gears 20 can be maintained at "zero".

The flexible carrier pin 41 is preferably made of a material with high strength and low Young's modulus from the viewpoint of high allowable torque and low backlash. Specific examples include a Ti-Ni (titanium nickel) alloy with a tensile strength of 1,000 MPa or more and a Young's modulus of 80 GPa or less, Rubber Metal (registered trademark), and the like.

The arrangement of the sun gear 10 is adjusted to a position where the meshing pitch circle diameters of the planetary gear 20 and the internal gear 31 match. Note that since the planetary gears 20 each have their own dimensional tolerances, the meshing pitch circle diameters of the plurality of planetary gears 20 and the internal gear 31 do not all match. Therefore, the matching of the meshing pitch circle diameters of the planetary gear 20 and the internal gear 31 here is a condition that they match with at least one or more planetary gears 20.

In the planetary gear mechanism 100, there is no need to provide a separate preload mechanism to suppress backlash as in the conventional case. Backlash between the sun gear 10 and the planetary gears 20 can be suppressed by the preload provided by the carrier pin 41 without increasing the number of parts. Therefore, the present invention can be applied to planetary gear devices of sizes in which conventionally it was not possible to incorporate a preload mechanism for reducing backlash. Specifically, in the past, it was difficult to suppress backlash when the outer diameter of the planetary gear device was approximately φ20 mm. However, the planetary gear device 1 of this embodiment can be applied even if it has an extremely small size, for example, an outer diameter of φ2 mm. In addition, when a planetary gear device with an outer diameter of φ2 mm to φ20 mm is represented by a module of each corresponding gear, the range corresponds to approximately 0.04 to 0.3.

In this embodiment, only the planetary gear mechanism 100 is configured inside the gear housing 30. However, it is also conceivable to add other mechanisms inside the gear housing 30. For example, in order to further increase the reduction ratio, in addition to the planetary gear mechanism 100, another planetary gear reduction mechanism (not shown) composed of multiple stages may be coaxially installed inside the gear housing 30. In this case, the planetary gear mechanism 100 that suppresses backlash is arranged at the final stage on the output shaft side. Further, the sun gear 10 is integrally attached to a final stage carrier of another planetary gear reduction mechanism.

Next, a planetary gear device 2, which is another embodiment of the present invention, will be described mainly using FIGS. 6 and 7. FIG. 6 is a longitudinal cross-sectional view of the planetary gear device 2. As shown in FIG. FIG. 7 is a sectional view taken along the line (B)-(B) in FIG. Note that the same components as those of the planetary gear device 1 of the first embodiment are designated by the same reference numerals, and redundant explanations will be omitted as appropriate.

The planetary gear mechanism 2 includes a planetary gear mechanism 100 and a second planetary gear mechanism 200. The planetary gear mechanism 100 and the second planetary gear mechanism 200 are coaxially connected by a connecting member 60.

The planetary gear mechanism 100 has the same configuration as that in the first embodiment. Backlash can be suppressed by maintaining the state in which the tooth surfaces of the sun gear 10 and the planet gears 20 are in contact with each other by preloading by the carrier pin 41.

The second planetary gear mechanism 200 is a multi-stage planetary gear reduction mechanism configured inside the second gear housing 70. In this embodiment, three second carriers 81, 82, 83 are connected in the axial direction to form a three-stage structure. Second sun gears 80S, 81S, 82S, a plurality of second planetary gears 91, 92, 93, a second internal gear 71 integrally formed inside the second gear housing 70, second carriers 81, 82, 83 It is composed of etc.

A second sun gear 81S is integrally fixed to the second carrier 81, which is the first stage on the input side among the three second carriers. A second sun gear 82S is integrally fixed to the second carrier 82, which is the middle stage. The second carrier 83, which is the final stage on the output side in the second planetary gear mechanism 200, has a rotating shaft portion 83a protruding toward the output side in the axial direction. The sun gear 10 of the planetary gear mechanism 100 is attached to the rotating shaft portion 83a.

Each second carrier 81, 82, 83 has a plurality of fixing holes 81h, 82h, 83h in each disc portion 81c, 82c, 83c, respectively. Second carrier pins 81p, 82p, 83p are inserted and fixed into the fixing holes 81h, 82h, 83h. The second carrier pins 81p, 82p, and 83p are in a state of protruding toward the axial input side.

Second planetary gears 91, 92, 93 are rotatably supported on each of the second carrier pins 81p, 82p, 83p. There are three second planetary gears for each second carrier, and they are arranged at equal intervals. For example, as shown in FIG. 7, there are three second planetary gears 93, which are rotatably supported by each of the three second carrier pins 83p on the second carrier 83, and evenly rotate the second sun gear 82S. They are arranged at intervals.

The second sun gears 80S, 81S, 82S and the second planetary gears 91, 92, 93 are non-tapered spur gears. Furthermore, no flexible material is used for the second carrier pins 81p, 82p, and 83p. That is, the second planetary gear mechanism 200 does not have a function of actively suppressing backlash.

An end cap 76 is integrally fixed to the axial input side of the second gear housing 70. A rotation input device (not shown) for the planetary gear device 2 is attached to the end cap 76 . A second sun gear 80S is attached integrally to the rotation shaft of this rotation input device.

The connecting member 60 has a substantially cylindrical shape. A bearing 61 and a bearing 62 are held on the cylindrical inner peripheral side of the connecting member 60. The rotating shaft portion 83a of the second carrier 83 is rotatably supported by the bearing 61 and the bearing 62.

A ring-shaped bush 84 is integrally attached to the rotating shaft portion 83a. The second carrier 83 is held in the axial direction by axially sandwiching the inner rings of the bearings 61 and 62 between a part of the disk portion 83c of the second carrier 83 and the bush 84.

The cylindrical outer circumferential surface of the connecting member 60, the cylindrical inner circumferential surface of the gear housing 30, and the cylindrical inner circumferential surface of the second gear housing 70 are fitted to connect the planetary gear mechanism 100 and the second planetary gear mechanism 200 coaxially. There is.

The connecting position of the second gear housing 70 in the axial direction with respect to the connecting member 60 is determined by the collar portion 60a of the connecting member 60. The connecting member 60 and the second gear housing 70 are press-fitted and fixed to each other at a predetermined position.

The connection position of the gear housing 30 to the connecting member 60 in the axial direction is determined by the arrangement of the sun gear 10, so that the sun gear 10 and the planetary gear 20 and the internal gear 31 are securely meshed, and the meshing pitch circle of the planetary gear 20 and the internal gear 31 is adjusted. Align it so that the diameters match. The gear housing 30 and the connecting member 60, which have been adjusted to be in a predetermined position, are welded together using a YAG laser or the like.

With the structure described above, when there is a rotational input to the second planetary gear mechanism 200, the rotation is transmitted to each second planetary gear 91 via the second sun gear 80S. The second planetary gear 91 rotates and revolves while meshing with the second sun gear 80S and the internal gear 31. The rotation of the second sun gear 81S, which is integral with the second carrier 81, transmits the input rotation to each carrier and each gear connected in the axial direction. The rotation transmitted at this time is largely decelerated by the second planetary gear mechanism 200. Finally, the revolution of the planetary gear 20 of the planetary gear mechanism 100 is output via the carrier 40 as rotation of the output shaft 42a.

In the planetary gear device 2 of this embodiment, since the planetary gear mechanism 100 is disposed at the final stage on the output shaft side, backlash can naturally be suppressed similarly to the planetary gear device 1 of the first embodiment. Further, by providing the planetary gear mechanism 200 as a connected speed reducer, it is possible to output the input rotation with a larger reduction ratio.

Furthermore, the planetary gear device 2 of this embodiment has the following effects.
In general, the axial thrust load generated by the influence of preload to suppress backlash is transmitted to the lower gear reducer and rotational input device (electromagnetic motor, etc.), which reduces mechanical efficiency. invite Therefore, it is desirable to complete the thrust load only with the backlash reduction mechanism (planetary gear mechanism 100). In contrast, in the planetary gear system 2, the thrust load applied to the sun gear 10 can be borne by the bearings 61 and 62 in the connecting member 60.

Further, by connecting the planetary gear mechanism 100 and the second planetary gear mechanism 200 via the connecting member 60, it is easy to align the position of the sun gear 10 in the axial direction inside the gear housing 30. That is, this is an effective means for adjusting the meshing pitch circle diameters of the planetary gear 20 and the internal gear 31 in the planetary gear mechanism 100, which is a backlash reduction mechanism, to match.

Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and can be modified as appropriate without changing the gist of the present invention.

1, 2: Planetary gear device 3: Input device 3a: Rotating shaft 10: Sun gear 20: Planetary gear 30: Gear housing 31: Internal gear 40: Carrier 41: Carrier pin 42: Output carrier 42a: Output shaft 42c: Disc Part 42h: Fixing hole 43: Sleeve 43a: Flange portion 50: Flanges 51, 52: Bearing 60: Connection member 60a: Flange portions 61, 62: Bearing 70: Second gear housing 71: Second internal gear 76: End cap 80S , 81S, 82S: Second sun gears 81, 82, 83: Second carriers 81c, 82c, 83c: Disc parts 81h, 82h, 83h: Fixing holes 81p, 82p, 83p: Second carrier pin 83a: Rotating shaft part 84: Bushes 91, 92, 93: Second planetary gear 100: Planetary gear mechanism 200: Second planetary gear mechanism

Claims (6)

A tapered sun gear,
a tapered planetary gear that meshes with the sun gear;
an internal gear that meshes with the planetary gear;
A carrier including a carrier pin that rotatably supports the planetary gear,
In the planetary gear device, the carrier pin is made of a flexible material.
The taper of the sun gear widens toward one axial direction of the sun gear,
2. The planetary gear apparatus according to claim 1, wherein the planetary gear is arranged such that a taper of the planetary gear widens in a direction substantially opposite to a taper of the sun gear.
The planetary gear device according to claim 1, wherein the sun gear, the planetary gear, and the internal gear have a module value of 0.04 to 0.3.
a first planetary gear mechanism including the sun gear, the planetary gear, the internal gear, and the carrier including the carrier pin;
a second planetary gear mechanism coaxially disposed on the input side with respect to the first planetary gear mechanism on the output side,
The second planetary gear mechanism includes a second sun gear, a second planetary gear, a second internal gear, and a second carrier including a second carrier pin,
For one second internal gear, there are a plurality of the second sun gears, the second planetary gears, and the second carriers,
The planetary gear device according to any one of claims 1 to 3, comprising a plurality of stages depending on the number of the second carriers.
The first planetary gear mechanism and the second planetary gear mechanism are connected by a connecting member,
5. The planetary gear apparatus according to claim 4, wherein the connecting member determines the axial position of the sun gear of the first planetary gear mechanism.
The first planetary gear mechanism and the second planetary gear mechanism are coaxially connected by the connecting member,
6. The sun gear of the first planetary gear mechanism is integrally fixed to the second carrier at the last stage on the output side among the second carriers in the plurality of stages of the second planetary gear mechanism. planetary gear system.

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