TW201938927A - Transmission device characterized by compactly arranging a reducer and a drive source along the direction of the rotary shaft of the annular gear - Google Patents

Abstract

A transmission device of one embodiment of the present invention includes: a first gear connected to a drive source; an annular gear having an outer circumferential surface and an inner circumferential surface, wherein the outer circumferential surface is provided with outer teeth engaged with the first gear, and the inner circumferential surface is provided with inner teeth; a second gear engaged with the inner teeth of the annular gear; a speed reducing part used to reduce and output an input from the second gear; and a bearing disposed at the radially inner side of being more near to annular gear than the inner teeth so as to rotatably support the annular gear.

Description

transmission

The present invention relates to a transmission device (for example, a reduction gear) that transmits a rotational driving force to a target device.

A transmission device that transmits a driving force from a driving source to a target device has been conventionally known. The target device is, for example, an industrial robot or a turntable. As an example of a conventional transmission, Patent Document 1 discloses a planetary gear reducer used in a drive mechanism for driving a wrist of an industrial robot. The planetary gear reducer decelerates a rotational driving force input from a driving motor as a driving source and transmits it to the wrist of the robot.

The planetary gear reducer has: a ring gear that inputs a rotational driving force from a drive motor; 3 pinions that mesh with the ring gear; and a reduction unit that reduces the rotation input from the pinion and outputs it to the robot Wrist. The ring gear includes external teeth and internal teeth. The pinion gear mounted on the output shaft of the drive motor meshes with the external teeth of the ring gear. The three pinions mentioned above mesh with the internal teeth of the ring gear. The ring gear is rotatably supported by the housing via a bearing provided on a radially outer side thereof.
[Prior technical literature]
[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 02-048193

[Problems to be solved by the invention]

In the wrist driving mechanism disclosed in Patent Document 1, the rotation axis of the ring gear is provided in parallel with the rotation axis of the driving source. Therefore, the driving source is disposed at a position shifted from the speed reducer in a direction along the rotation axis of the ring gear. Therefore, in the aforementioned conventional reducer, the reducer and the drive source cannot be compactly arranged in a direction along the rotation axis of the ring gear.

Further, in the planetary gear reducer described above, a bearing that supports the ring gear on the support body is arranged radially outward of the ring gear. Therefore, the size of the planetary gear reducer becomes larger in the radial direction of the ring gear.

An object of the present invention is to solve or alleviate at least part of the problems described above. One of the more specific objects of the present invention is to provide a transmission device capable of being compacted.
[Technical means to solve the problem]

A transmission device according to an embodiment of the present invention includes a first gear connected to a driving source, and a ring gear having an outer peripheral surface and an inner peripheral surface. The outer peripheral surface is provided with external teeth that mesh with the first gear. The peripheral surface is provided with internal teeth; a second gear that meshes with the internal teeth of the ring gear; a speed reduction unit that reduces input from the second gear and outputs; and a bearing that is arranged closer to the internal teeth than the internal teeth A radially inner side of the ring gear rotatably supports the ring gear.

A transmission device according to an embodiment of the present invention includes a first gear connected to a driving source, and a ring gear having an outer peripheral surface and an inner peripheral surface. The outer peripheral surface is provided with external teeth that mesh with the first gear. The peripheral surface is provided with internal teeth; a second gear that meshes with the internal teeth of the ring gear; a base portion; a reduction portion having a fixed portion and an output portion, the fixed portion is provided in a manner that does not rotate relative to the base portion, The output section rotates relative to the base at a rotational speed that has been decelerated from the speed of the second gear; and a bearing that rotates the ring gear relative to the base at a radially inner side of the ring gear than the internal teeth. Way to support.

A transmission device according to an embodiment of the present invention includes a first gear connected to a driving source and rotating around a first rotation axis; and a ring gear having an outer peripheral surface and an inner peripheral surface, the outer peripheral surface being provided with the first The gear meshes with external teeth. The inner peripheral surface is provided with internal teeth. The ring gear rotates around a second rotation axis extending in a direction different from the first rotation axis. The second gear is connected to the internal teeth of the ring gear. Meshing; and a reduction section that decelerates and outputs the input from the second gear.

In one embodiment of the present invention, the internal teeth are disposed on a first imaginary plane orthogonal to the second rotation axis and passing through the external teeth, the closer to the second rotation axis than the external teeth.

In one embodiment of the present invention, the speed reduction unit has a fixed portion and an output portion, and the fixed portion is provided so as not to rotate relative to the base portion. The output portion is provided inside the fixed portion, and 2 The speed of the gear is reduced relative to the above-mentioned base.

In one embodiment of the present invention, the transmission device includes a main bearing disposed between the fixed portion and the output portion, and at least a portion of the first gear is disposed on an outer peripheral surface of the main bearing and an outer peripheral surface of the fixed portion. between.

In one embodiment of the present invention, the main bearing is disposed on a second imaginary plane orthogonal to the second rotation axis and passing through the first gear, and is closer to the second rotation axis than the first gear.

In one embodiment of the present invention, the fixed portion has a concave portion on an outer peripheral surface thereof, and at least a part of the first gear is disposed in the concave portion.

In one embodiment of the present invention, the speed reduction unit includes a swing gear that is swung by the rotation of the second gear, and the swing gear is at a third hypothesis orthogonal to the second rotation axis and passing through the first gear. The surface is disposed closer to the second rotation shaft than the first gear.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, a transmission device according to an embodiment of the present invention and a rotation device including the same will be described with reference to FIGS. 1 to 4. FIG. 1 is a schematic view schematically showing a rotating device including a transmission device according to an embodiment of the present invention, and FIG. 2 is a schematic view showing a part of an internal structure of a rotating device according to an embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing a cross-section taken along the line A-A in FIG. 2, and FIG. 4 is a cross-sectional view schematically showing a cross-section taken along the line B-B in FIG. 3. The rotating device shown is used to rotate, for example, a wrist or a turntable of an industrial robot.

The illustrated rotating device includes a driving source 5 and a speed reducer 10 that transmits rotation from the driving source 5 to a target device. The drive source 5 is, for example, an electric motor. The reducer 10 decelerates the rotation input from the drive source 5 and outputs it to a target device (not shown) as a drive target. The transmission device to which the present invention can be applied is not limited to the speed reducer 10.

The speed reducer 10 includes a gear unit 100 that transmits rotation from the drive source 5, a base portion 15, and a speed reduction portion 50 supported by the base portion 15. A through hole is provided in the speed reducer 10, and a cylindrical central pipe 25 is provided in the through hole. The deceleration section 50 decelerates the rotation input from the gear unit 100 and outputs the decelerated rotation.

Next, the gear unit 100 will be described more specifically. The gear unit 100 includes a spur gear 1, an input gear 2, and a ring gear 3. The input gear 2 is connected to the drive shaft 111 of the drive source 5 and rotates around the first rotation axis by a driving force input from the drive source 5.

In the illustrated embodiment, the spur gear 1 is a spur gear. The spur gear 1 applicable to the present invention is not limited to a spur gear. As the spur gear 1, any gear capable of transmitting the rotation of the ring gear 3 to the reduction unit 50 (specifically, a crankshaft 80 described later) can be used. In the illustrated embodiment, the gear unit 100 has three spur gears 1, but the number of spur gears 1 provided in the gear unit 100 may be more than three or less than three.

The ring gear 3 is supported by the base portion 15 so as to rotate about a rotation axis RCX. The ring gear 3 includes a support member 7 supported by the base 15 and a ring-shaped ring member 8. The supporting member 7 has a disc-shaped body portion 7a and a convex seat portion 7b extending from the radially inner end of the body portion 7a in the X2 direction. The boss portion 7b has a substantially cylindrical shape. In the illustrated embodiment, the support member 7 and the ring member 8 are independent members, and the ring member 8 is connected to the support member 7 by a bolt 14. The support member 7 and the ring member 8 may also have a one-piece structure. The ring gear 3 includes internal teeth 4 and external teeth 6. More specifically, the ring member 8 of the ring gear 3 includes internal teeth 4 and external teeth 6. The internal teeth 4 are provided along the inner peripheral surface of the ring member 8 and mesh with the spur gear 1. The external teeth 6 are provided along the outer peripheral surface of the ring member 8 and mesh with the input gear 2. The input gear 2 is an example of the first gear described in the scope of the patent application. The spur gear 1 is an example of the second gear described in the patent application scope.

An imaginary plane P1 orthogonal to the rotation axis RCX and passing through the external teeth 6 is shown in FIG. 3. Both the internal teeth 4 and the external teeth 6 are arranged on the virtual plane P1. In other words, the imaginary plane P1 passes through both the internal teeth 4 and the external teeth 6. The imaginary plane P1 is an example of the first imaginary plane in the scope of patent application. In the previous reducer, the teeth of the gear meshing with the input gear and the teeth of the gear meshing with the spur gear are disposed at positions shifted in the direction of the central axis of the reducer. In contrast, in the embodiment shown in the figure, the external teeth 6 meshing with the input gear 2 and the internal teeth 4 meshing with the spur gear 1 are arranged on the imaginary plane P1. With this configuration, the reduction of Dimensions in the center axis RCX direction. The spur gear 1 and the bolt 14 are also arranged on this imaginary plane P1. With this configuration, the size of the central axis RCX direction of the reducer 10 can be further reduced.

The ring gear 3 rotates around a rotation axis RCX (second rotation axis). The ring gear 3 is disposed such that its rotation axis RCX is not parallel to the rotation axis (first rotation axis) of the input gear 2. In the illustrated embodiment, the rotation axis RCX of the ring gear 3 coincides with the axis passing through the center of the cylindrical through-hole provided at the center of the reduction gear 10. Therefore, in this specification, the rotating shaft RCX may be referred to as (the center of the speed reducer 10) RCX. The second rotation axis extends in a direction different from the first rotation axis. Therefore, the transmission direction of the driving force from the driving source 5 is changed by the input gear 2 and the ring gear 3. In the illustrated embodiment, the input gear 2 and the ring gear 3 constitute a helical gear. In addition to the helical gear, the input gear 2 and the ring gear 3 may be a helical gear, a worm gear, or a gear other than the above that can change the direction of power transmission.

The specific shape, arrangement, and number of each gear as a constituent element of the gear unit 100 are not limited to those shown in the drawings.

Next, the speed reduction unit 50 will be described more specifically. The speed reduction unit 50 includes a crankshaft 80, a crankshaft bearing 84, a swing gear unit 70, a housing 11, a bracket 60, and a pin 20 coupled to the spur gear 1.

The crankshaft 80 includes a shaft body 80a, an eccentric portion 81, and an eccentric portion 82. The shaft body 80a is a cylindrical member extending in a direction parallel to the central axis RCX. The eccentric portion 81 and the eccentric portion 82 are cylindrical members. The eccentric portion 81 and the eccentric portion 82 are eccentric from the shaft body 80a. The phase of the eccentric portion 81 and the phase of the eccentric portion 82 are shifted from each other by 180 °. The eccentric portion 82 is provided closer to the X2 side than the eccentric portion 81 in the center axis RCX direction. The crankshaft 80 is fixed to the spur gear 1. In other words, the crankshaft 80 is provided so as not to rotate relative to the spur gear 1.

A plurality of crankshaft bearings 84 are provided on the radially outer side of the eccentric portions 81 and 82. The crankshaft bearing 84 is, for example, a needle bearing.

The oscillating gear portion 70 includes a first oscillating gear 71 and a second oscillating gear 72 provided on the X2 side of the first oscillating gear 71 in the direction of the central axis RCX. The first swing gear 71 is attached to the eccentric portion 81 via a crankshaft bearing 84. Similarly, the second swing gear 72 is attached to the eccentric portion 82 via a crankshaft bearing 84. The first swinging gear 71 has a central hole 71c at the center in the radial direction, and three shaft holes 71b around the central hole 71c. The second swinging gear 72 has a center hole 72c at the center in the radial direction, and three shaft holes 72b around the center hole 72c. The first swing gear 71 has external teeth 71a, and the second swing gear 72 has external teeth 72a. The number of external teeth 71 a of the first swing gear 71 is the same as the number of external teeth 72 a of the second swing gear 72. In the illustrated embodiment, the number of pins 20 is only one more than the number of teeth of the external teeth 71a (external teeth 72a).

A casing 11 is provided on a radially outer side of the swing gear portion 70. The casing 11 includes a casing body 11b having a cylindrical shape and a flange 11a provided on the radially outer side of the casing body 11b. The case body 11b has an outer peripheral surface 11b1. The outer peripheral surface 11b1 of the case body 11b is in contact with the inner peripheral surface of the flange 11a. A motor flange 112 is attached to the outer peripheral surface 11b1 of the case body 11b. The drive source 5 is mounted on the housing body 11 b and the base 15 via the motor flange 112. A concave portion 11b2 recessed inward in the radial direction is provided on the outer peripheral surface 11b1 of the case body 11b. The recessed portion 11b2 is provided at a position facing the drive source 5 in the outer peripheral surface 11b1 of the case body 11b. As shown in FIG. 3, at least a part of the input gear 2 that rotates from the drive shaft 111 of the drive source 5 is housed in the recess 11 b 2.

The inner wall of the casing body 11b is provided with a plurality of grooves extending in the direction of the rotation axis RCX. A pin 20 is provided in each of the plurality of grooves. The pin 20 is a cylindrical member extending in the direction of the rotation axis RCX. Thereby, the pin 20 is held by the case body 11b.

The flange 11 a is fastened to the housing body 11 b and the base 15 by bolts. The flange 11 a does not rotate relative to the case body 11 b and the base 15. The case 11 is an example of the fixing portion described in the scope of the patent application.

A bracket 60 is provided on a radially inner side of the casing 11. The bracket 60 includes a first bracket body 61 and a second bracket body 62. A first swing gear 71 and a second swing gear 72 are arranged between the first bracket body 61 and the second bracket body 62. The first bracket body 61 and the second bracket body 62 have a through hole extending in the center axis RCX direction in the center of the first bracket body 61 and the second bracket body 62. The first bracket body 61 has three shafts 63 protruding in the X2 direction from the lower surface thereof. The shaft 63 extends to the upper surface of the second bracket body 62 through the shaft hole 71 b of the first swing gear 71 and the shaft hole 72 b of the second swing gear 72. The second bracket body 62 is attached to the shaft 63 by a bolt 64. The first bracket body 61 and the second bracket body 62 do not rotate relative to each other. The first bracket body 61 and the second bracket body 62 may have an integrated one-piece structure.

The first bracket body 61 is provided in the housing 11 via a first main bearing 91. The second bracket body 62 is provided in the housing 11 via a second main bearing 92. A part of the outer peripheral surface of the second main bearing 92 is also in contact with the inner peripheral surface of the flange 11a. Accordingly, the first bracket body 61 and the second bracket body 62 are supported to be relatively rotatable relative to the casing 11.

The cradle 60 is connected to the target device. The target device is a turntable, an arm of an industrial robot, or a rotatable device other than the above. The bracket 60 is an example of the output unit described in the patent application scope.

The base portion 15 has a disc-shaped bottom portion 15a and a convex portion 15b extending from the radially inner end of the bottom portion 15a in the X1 direction. The base portion 15 is connected to the flange 11a at the radially outer end of the bottom portion 15a. The boss portion 15b has a substantially cylindrical shape.

A first bearing 13a and a second bearing 13b are provided between the outer peripheral surface of the convex seat portion 15b of the base portion 15 and the inner peripheral surface of the convex seat portion 7b of the support member 7. The second bearing 13b is disposed closer to the X2 side than the first bearing 13a. The first bearing 13 a and the second bearing 13 b are arranged radially inward of the inner teeth 4 of the ring gear 3. That is, the first bearing 13 a and the second bearing 13 b are disposed closer to the center axis RCX than the internal teeth 4 of the ring gear 3. In this way, the ring gear 3 is supported by the first bearing 13a and the second bearing 13b so as to be rotatable about the center axis RCX. In the previous reducer, a bearing supporting a ring gear was provided radially outward of the ring gear. In contrast, in the embodiment shown in the figure, the first bearing 13a and the second bearing 13b are arranged on the radially inner side of the reducer 10 than the internal teeth 4, so the diameter of the reducer 10 can be reduced by this arrangement. Dimensions (direction orthogonal to the central axis RCX).

A sealing member 16 is provided between the inner peripheral surface of the boss portion 15 b and the outer peripheral surface of the central pipe 25. The sealing member 16 is arranged in a region between an end on the X1 side of the first bearing 13a and an end on the X2 side of the second bearing 13b. In the illustrated embodiment, the first bearing 13a and the second bearing 13b supporting the ring gear 3 are not directly mounted on the central pipe 25, but are mounted on a convex seat portion 15b provided on the radially outer side of the central pipe 25. Since the sealing member 16 is provided between the boss portion 15b and the central pipe 25, the sealing member 16 can be disposed in a position overlapping the at least one of the first bearing 13a and the second bearing 13b in the central axis RCX direction. With this arrangement, the size in the direction of the center axis RCX of the reducer 10 can be reduced.

Next, the arrangement of the input gear 2 will be described. An imaginary plane P2 that is orthogonal to the rotation axis RCX and passes through the second main bearing 92 is shown in FIG. 3. The imaginary plane P2 is an example of the second imaginary plane in the scope of patent application. Both the second main bearing 92 and the input gear 2 are arranged on the virtual plane P2. In other words, the imaginary plane P2 passes through both the second main bearing 92 and the input gear 2. The second main bearing 92 is disposed on the virtual plane P2 closer to the center axis RCX than the input gear 2. With this arrangement, the size in the direction of the center axis RCX of the reducer 10 can be reduced. In the illustrated embodiment, the driving shaft 111 of the driving source 5 is also arranged on the virtual plane P2. With this arrangement, the size in the direction of the center axis RCX of the reducer 10 can also be reduced.

FIG. 3 shows an imaginary plane P3 orthogonal to the rotation axis RCX and passing through the second swing gear 72. The imaginary plane P3 is an example of the third imaginary plane in the scope of patent application. The second swing gear 72 and the input gear 2 are both disposed on the virtual plane P3. In other words, the virtual plane P3 passes through both the second swing gear 72 and the input gear 2. In the illustrated example, the imaginary plane P3 passes near the upper end of the input gear 2. The second swing gear 72 is disposed on the virtual plane P3 closer to the center axis RCX than the input gear 2. With this arrangement, the size in the direction of the center axis RCX of the reducer 10 can be reduced.

As shown in FIG. 3, at least a part of the input gear 2 is disposed in a direction orthogonal to the central axis RCX at a position between the outer peripheral surface 91a of the main bearing 91 (or the outer peripheral surface 92a of the main bearing 92) and the case body 11b Between the positions of the outer peripheral surface 11b1. With this arrangement, the size in the radial direction (direction orthogonal to the central axis RCX) of the speed reducer 10 can be reduced.

Next, a speed reducer according to another embodiment of the present invention will be described with reference to FIG. 5. FIG. 5 is an enlarged view showing a part of a cross section of a speed reducer according to another embodiment of the present invention. In the embodiment shown in FIG. 5, the configuration of the ring gear 3 is different from the embodiment shown in FIG. 3. In the embodiment shown in FIG. 5, the ring gear 3 includes a support member 7, an external tooth member 8a, and an internal tooth member 8b. Both the external tooth member 8a and the internal tooth member 8b have a ring shape. External teeth 6 are provided on the outer peripheral surface of the external tooth member 8a, and internal teeth 4 are provided on the internal peripheral surface of the internal tooth member 8b. The supporting member 7 has a disc-shaped body portion 7a and a convex seat portion 7b extending from the radially inner end of the body portion 7a in the X2 direction. The external tooth member 8a, the internal tooth member 8b, and the body portion 7a of the support member 7 are connected by a bolt 14.

Next, the operation of the speed reducer 10 will be described. When the rotation from the drive source 5 is input to the input gear 2, the ring gear 3 rotates around the center axis RCX in conjunction with the rotation of the input gear 2. The rotation of the ring gear 3 is transmitted to the spur gear 1 that meshes with the internal teeth 4 of the ring gear. When the spur gear 1 rotates, the eccentric portion 81 and the eccentric portion 82 of the crankshaft 80 rotate eccentrically. By the eccentric rotation of the eccentric portion 81 and the eccentric portion 82, the first swing gear 71 and the second swing gear 72 swing and rotate. At this time, the center axis CX of the first swing gear 71 and the center axis CX2 of the second swing gear 72 orbit the rotation center axis RCX of the bracket 60. Therefore, the outer teeth 71 a of the first swing gear 71 and the outer teeth 72 a of the second swing gear 72 mesh with the pin 20, and the first swing gear 71 and the second swing gear 72 move around in the housing body 11 b. Each time the crankshaft 80 makes one revolution, the first swing gear 71 rotates with respect to the housing 11 and the difference between the number of pins 20 and the number of teeth of the external teeth 71a is an amount corresponding to one tooth. In this way, the rotation of the crankshaft 80 is reduced to a reduction ratio of “1 / the number of teeth of the external teeth 71 a” and transmitted to the carrier 60. As a result, the bracket 60 is rotated relative to the housing 11 and the base 15 at a rotation speed that has been decelerated from the rotation speed of the crankshaft 80. As described above, the rotation input from the drive source 5 to the speed reducer 10 is reduced and output from the bracket 60 to the target device.

The sizes, materials, and arrangements of the constituent elements described in this specification are not limited to those explicitly described in the embodiment, and the constituent elements can be in any manner having dimensions, materials, and arrangements that can be included in the scope of the invention Variety. In addition, constituent elements not explicitly described in the present specification may be added to the embodiments described, or a part of the constituent elements described in each embodiment may be omitted.

Each of the above-described embodiments may be appropriately combined. An aspect realized by combining a plurality of embodiments may also become an embodiment of the present invention.

1‧‧‧ 2nd gear (spur gear)

2‧‧‧ 1st gear (input gear)

3‧‧‧ ring gear

4‧‧‧ Internal tooth

5‧‧‧Drive source

6‧‧‧ external teeth

7‧‧‧ supporting components

7a‧‧‧Body

7b‧‧‧ convex seat

8‧‧‧ ring member

8a‧‧‧Outer teeth member

8b‧‧‧Internal gear member

10‧‧‧ Reducer

11‧‧‧shell

11a‧‧‧ flange

11b‧‧‧shell body

11b1‧‧‧outer surface

11b2‧‧‧ recess

13‧‧‧bearing

13a‧‧‧The first bearing

13b‧‧‧Second bearing

14‧‧‧ Bolt

15‧‧‧ base

15a‧‧‧ bottom

15b‧‧‧ convex seat

16‧‧‧Sealing member

20‧‧‧pin

25‧‧‧ Central tube

50‧‧‧ Reduction section

60‧‧‧ Bracket

61‧‧‧The first bracket body

62‧‧‧ 2nd bracket body

63‧‧‧axis

64‧‧‧ Bolt

70‧‧‧Swing gear section

71‧‧‧1st swing gear

71a‧‧‧outer tooth

71b‧‧‧shaft hole

71c‧‧‧center hole

72‧‧‧ 2nd swing gear

72a‧‧‧outer teeth

72b‧‧‧shaft hole

72c‧‧‧center hole

80‧‧‧ crankshaft

80a‧‧‧shaft body

81‧‧‧eccentric

82‧‧‧eccentric

84‧‧‧ crankshaft bearings

91‧‧‧The first main bearing

91a‧‧‧outer surface

92‧‧‧Second main bearing

92a‧‧‧outer surface

100‧‧‧Gear unit

111‧‧‧Drive shaft

112‧‧‧Motor flange

CX1‧‧‧center axis

CX2‧‧‧center axis

P1‧‧‧imaginary noodles

P2‧‧‧imaginary noodles

P3‧‧‧imaginary noodles

RCX‧‧‧Rotary shaft

FIG. 1 is a schematic diagram of a rotating device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a part of an internal structure of a rotating device according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating the details of a rotating device according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view schematically showing a cross section of a speed reducer provided in the rotating device of FIG. 3.

FIG. 5 is an enlarged view showing a part of a gear unit according to another embodiment of the present invention.

Claims (12)

A transmission device includes: A first gear connected to a drive source; The ring gear has an outer peripheral surface and an inner peripheral surface, the outer peripheral surface is provided with external teeth that mesh with the first gear, and the inner peripheral surface is provided with internal teeth; A second gear that meshes with the internal teeth of the ring gear; A decelerating section that decelerates and outputs an input from the second gear; and The bearing is disposed on the radially inner side of the ring gear than the internal teeth, and rotatably supports the ring gear. A transmission device includes: A first gear connected to a drive source; The ring gear has an outer peripheral surface and an inner peripheral surface, the outer peripheral surface is provided with external teeth that mesh with the first gear, and the inner peripheral surface is provided with internal teeth; A second gear that meshes with the internal teeth of the ring gear; Base A speed reduction section having a fixed section provided so as not to rotate relative to the base section, and the output section rotated relative to the base section at a rotation speed after being decelerated from the rotation speed of the second gear; and The bearing supports the ring gear on a radially inner side of the ring gear than the internal teeth so as to be rotatable relative to the base. A transmission device includes: A first gear connected to a driving source and rotating around a first rotation axis; The ring gear has an outer peripheral surface and an inner peripheral surface. The outer peripheral surface is provided with external teeth that mesh with the first gear. The inner peripheral surface is provided with internal teeth. The extended second rotation axis rotates; A second gear that meshes with the internal teeth of the ring gear; and The speed reduction unit reduces the speed of the input from the second gear and outputs the speed. The transmission as claimed in item 3, wherein The internal teeth are arranged closer to the second rotation axis than the external teeth on a first imaginary plane that is orthogonal to the second rotation axis and passes through the external teeth. If the transmission of claim 3 or 4 has a base, The speed reduction section includes a fixed section and an output section. The fixed section is provided so as not to rotate with respect to the base section. The output section is provided inside the fixed section and is rotated at a relative speed after decelerating from the speed of the second gear. Rotate at the base. If the transmission device of claim 5 is provided with a main bearing disposed between the fixed portion and the output portion, At least a part of the first gear is disposed between the outer peripheral surface of the main bearing and the outer peripheral surface of the fixed portion. The transmission of any one of claims 3 to 6, wherein The main bearing is disposed on a second imaginary plane orthogonal to the second rotation axis and passing through the first gear, and is closer to the second rotation axis than the first gear. If the transmission of claim 5 or 6, in which The fixed portion has a concave portion on the outer peripheral surface, At least a part of the first gear is disposed in the concave portion. The transmission of any one of claims 3 to 8, wherein The speed reduction unit has a swing gear that swings by the rotation of the second gear, The swing gear is disposed closer to the second rotation shaft than the first gear on a third virtual plane orthogonal to the second rotation shaft and passing through the first gear. A transmission device includes: A first gear connected to a drive source; The ring gear has an outer peripheral surface and an inner peripheral surface, the outer peripheral surface is provided with external teeth that mesh with the first gear, and the inner peripheral surface is provided with internal teeth; A second gear that meshes with the internal teeth of the ring gear; and The bearing is disposed at a position radially inward of the ring gear than the internal teeth, and rotatably supports the ring gear. A transmission device includes: A first gear connected to a drive source; The ring gear has an outer peripheral surface and an inner peripheral surface, the outer peripheral surface is provided with external teeth that mesh with the first gear, and the inner peripheral surface is provided with internal teeth; A second gear that meshes with the internal teeth of the ring gear; Base; and A bearing is provided between the base and the ring gear. A transmission device includes: A first gear connected to a driving source and rotating around a first rotation axis; The ring gear has an outer peripheral surface and an inner peripheral surface. The outer peripheral surface is provided with external teeth that mesh with the first gear. The inner peripheral surface is provided with internal teeth. Rotation of the extended second rotation axis; and The second gear meshes with the internal teeth of the ring gear.