Power transmission device

Abstract

To provide a power transmission device that can reduce the number of parts, thereby lowering costs and assembly man-hours. [Solution] The power transmission device 1 comprises a first rotating body 10 having a main shaft portion 11a and an eccentric portion 11b eccentric to the main shaft portion 11a; a second rotating body 20 having a first external gear 61 and a second external gear 62 provided radially outward from the eccentric portion 11b around the first axis O1, a first internal gear 22 that meshes with the first external gear 61; a third rotating body 30 having a second internal gear 32 that meshes with the second external gear 62; and a fourth rotating body 40 arranged radially outward from the first rotating body 10, the second rotating body 20, and the third rotating body 30, and having a rotating member 41 that rotates around the first axis O1 in conjunction with the rotation of the first external gear 61.

Description

Technical Field

[0005] , , ,

[0001] The present disclosure relates to a power transmission device.

Background Art

[0002] Power transmission devices such as speed reducers and speed increasers transmit power from the input side to the output side through a plurality of meshing gears. For example, Patent Document 1 discloses a speed reduction device provided with a so-called rocking internal meshing planetary gear mechanism. This type of planetary gear mechanism includes an input shaft having a pinion gear, an input gear having an eccentric shaft and meshing with the pinion gear, an external gear that swings and rotates by the eccentric shaft, an internal gear that meshes with the external gear, and a casing integrated with the internal gear. The input gear and the eccentric shaft are provided in three sets at intervals in the circumferential direction on the outer side in the radial direction of the input shaft.

Prior Art Documents

Patent Documents

[0006] (2) In the power transmission device according to the embodiment of (1) above, each of the first rotating body, the second rotating body, the third rotating body, and the fourth rotating body has a mounting portion to which an external member can be attached, and any one of the first rotating body, the second rotating body, the third rotating body, and the fourth rotating body can be fixed to an object to be attached as an external member via the mounting portion of any one of them, any other one of the first rotating body, the second rotating body, the third rotating body, and the fourth rotating body can be connected to a drive shaft that rotates the first rotating body, the second rotating body, the third rotating body, and the fourth rotating body as an external member via the mounting portion of any one of the other, and each of the remaining two of the first rotating body, the second rotating body, the third rotating body, and the fourth rotating body can be connected to two objects to be driven as external members via the mounting portions of each of the remaining two. According to this embodiment, the first rotating body, second rotating body, third rotating body, and fourth rotating body can be appropriately connected to the mounting object, drive shaft, and driven object. This allows the power transmission device to be used in various ways, increasing its versatility.

[0007] (3) In the power transmission device according to the embodiment of (1) or (2) above, it is preferable that the second rotating body has a first extension portion that extends to the first side in the axial direction relative to the first internal gear and has the mounting portion formed thereon, and the third rotating body has a second extension portion that extends to the second side in the axial direction relative to the second internal gear and has the mounting portion formed thereon. According to this embodiment, the second rotating body and the third rotating body can be connected to an external member via the mounting portion of the first extension and the mounting portion of the second extension.

[0008] (4) In a power transmission device according to any of the embodiments of (1) to (3) above, it is preferable that the second rotating body, the third rotating body, and the fourth rotating body are formed to surround the first rotating body on the radially outward side of the first rotating body. According to this embodiment, the second, third, and fourth rotating bodies can each be formed to surround the first rotating body, which, compared to, for example, a configuration using multiple sets of planetary gear mechanisms, reduces the number of parts and allows for miniaturization in the radial direction.

[0009] (5) In a power transmission device according to any of the embodiments of (1) to (4) above, the fourth rotating body is preferably a housing that covers the first rotating body, the second rotating body, and the third rotating body from the radially outer side. According to this embodiment, the fourth rotating body also serves as the housing, allowing the power transmission device to be constructed with fewer parts.

[0010] (6) In a power transmission device according to any of the embodiments of (1) to (5) above, it is preferable that the number of teeth of the first external gear is less than the number of teeth of the first internal gear, and the number of teeth of the second external gear is less than the number of teeth of the second internal gear. According to this embodiment, the speed can be changed between the first rotating body, the second rotating body, and the third rotating body by the difference in the number of teeth between the first external gear and the second internal gear, and between the second external gear and the second internal gear.

[0011] (7) In the power transmission device according to the embodiment of (6) above, it is preferable that the number of teeth of the first internal gear is different from the number of teeth of the second internal gear. According to this embodiment, the gear ratio can be made different between the second rotating body and the third rotating body.

[0012] (8) In a power transmission device according to any of the embodiments of (1) to (7) above, it is preferable that one of the first external gear and the rotating member has a pin that protrudes toward the other of the first external gear and the rotating member, and that the other member has an inner diameter larger than the outer diameter of the pin and has a pin insertion portion into which the pin is inserted. According to this aspect, rotation can be transmitted between a first external gear that revolves around a first axis and a rotating member of a fourth rotating body by a pin insertion portion and a pin inserted into the pin insertion portion, and the first rotating body and the second rotating body can be rotated at a predetermined speed ratio.

Effect of the Invention

[0013] According to one aspect of the present disclosure, the number of components can be reduced, and the cost and the number of assembly steps can be reduced.

Brief Description of the Drawings

[0014] [Figure 1] It is a perspective view of a power transmission device according to an embodiment of the present disclosure. [Figure 2] It is a perspective view of the above power transmission device viewed from a direction different from that of FIG. 1. [Figure 3] It is a cross-sectional view taken along the arrow III-III in FIG. 1. [Figure 4] It is a perspective view showing a main body shaft portion and an eccentric portion of a first rotating body. [Figure 5] It is a perspective view mainly showing a first rotating body, a first external gear, a first internal gear of a second rotating body, and a rotating member. [Figure 6] It is a perspective view showing a first rotating body, an external gear module, a first internal gear, and a second internal gear. [Figure 7] It is a view showing an example of an installation mode of the power transmission device.

Mode for Carrying Out the Invention

[0015] Next, embodiments of the present disclosure will be described based on the drawings. In the embodiments and modifications described below, corresponding configurations may be denoted by the same reference numerals and description thereof may be omitted. In the following description, expressions indicating relative or absolute arrangements such as "parallel", "orthogonal", "center", "coaxial", etc. not only represent such strict arrangements, but also represent states in which they are relatively displaced with tolerances and angles or distances that can obtain the same function.

[0016] [Power Transmission Device 1] FIG. 1 is a perspective view of the power transmission device 1. FIG. 2 is a perspective view of the power transmission device 1 viewed from a direction different from that of FIG. 1. FIG. 3 is a sectional view taken along the arrow III-III of FIG. 1. The power transmission device 1 shown in FIGS. 1 to 3 is mounted on an industrial machine such as a stirring device. The power transmission device 1 may be mounted on a robot, a medical actuator, or the like. The power transmission device 1 is attached to an attachment object such as the main body of an industrial machine. The power transmission device 1 outputs the torque input from a drive source (such as a motor) provided on the attachment object to a plurality of drive objects (output devices) arranged on the output side of the power transmission device 1.

[0017] The power transmission device 1 includes a first rotating body 10, an external gear module 60 (see FIG. 3), a second rotating body 20 (see FIGS. 2 and 3), a third rotating body 30 (see FIGS. 1 and 2), and a fourth rotating body 40. Each of the first rotating body 10, the second rotating body 20, the third rotating body 30, and the fourth rotating body 40 is connected to external members 101 to 104. Any one of the external members 101 to 104 is an input-side drive source that drives the power transmission device 1 or a connection member for connecting to the drive source. Any one of the other external members 101 to 104 is a fixed-side attachment object to which the power transmission device 1 is fixed or a connection member for connecting to the attachment object. The remaining two of the external members 101 to 104 are output-side drive objects (first drive object, second drive object) or connection members for connecting to the drive objects. As will be described in detail later, the power transmission device 1 can attach the drive source, the attachment object, and the two drive objects to the first rotating body 10, the second rotating body 20, the third rotating body 30, and the fourth rotating body 40 in a plurality of installation modes. That is, each of the first rotating body 10, the second rotating body 20, the third rotating body 30, and the fourth rotating body 40 is connected to any one of the drive source, the attachment object, and the drive object according to the installation mode of the power transmission device 1. Thereby, the drive source and the plurality of drive objects are indirectly connected via the power transmission device 1 attached to the attachment object.

[0018] <First Rotating Body 10> Figure 4 is a perspective view showing the main shaft portion 11a and the eccentric portion 11b of the first rotating body 10. As shown in Figures 3 and 4, the first rotating body 10 has a main shaft portion 11a, an eccentric portion 11b, and a balancer 11c (see Figure 3). The main shaft portion 11a extends along the first axis O1. In the following description, the direction along the first axis O1 is referred to as the axial direction, the direction intersecting the first axis O1 when viewed from the axial direction is referred to as the radial direction, and the direction revolving around the first axis O1 is referred to as the first circumferential direction.

[0019] As shown in Figure 3, bearings 51 and 52 are provided at both axial ends of the main shaft portion 11a. Bearing 51 is interposed between the second rotating body 20 and the main shaft portion 11a. Bearing 52 is interposed between the third rotating body 30 and the main shaft portion 11a. The main shaft portion 11a is rotatably mounted around the first axis O1 relative to the second rotating body 20 and the third rotating body 30 by the bearings 51 and 52.

[0020] As shown in Figure 3, a first mounting portion (mounting portion) 14 is formed at the first axial end of the main shaft portion 11a, to which an external member 101 can be attached. In this embodiment, the first mounting portion 14 is, for example, a keyway. The main shaft portion 11a and the external member 101 are configured to rotate integrally around the first axis O1 via a key (not shown) fitted into the first mounting portion.

[0021] As shown in Figures 3 and 4, the eccentric portion 11b is formed in the axial central part of the main shaft portion 11a. The eccentric portion 11b bulges radially outward from the main shaft portion 11a. The eccentric portion 11b is formed in a cylindrical shape centered on a second axis O2 that is eccentric by an eccentricity e with respect to the first axis O1. The eccentric portion 11b revolves around the first axis O1 as the first rotating body 10 (main shaft portion 11a) rotates around the first axis O1.

[0022] Figure 5 is a perspective view mainly showing the first rotating body 10, the first external gear 61, the first internal gear 22 of the second rotating body 20, and the rotating member 41. As shown in Figure 3, the balancer 11c counteracts the moment acting on the main shaft portion 11a due to the rotation of the eccentric portion 11b, thereby balancing the weight of the first rotating body 10. The balancer 11c is provided on the portion of the main shaft portion 11a located on the first axial side relative to the eccentric portion 11b (the portion located between the eccentric portion 11b and the mounting portion 14). As shown in Figures 3 and 5, the balancer 11c is formed in a fan shape when viewed from the axial direction. The balancer 11c protrudes from the main shaft portion 11a in the opposite direction to the eccentricity of the eccentric portion 11b.

[0023] <External tooth module 60> The external gear module 60 is provided radially outside the eccentric portion 11b. The external gear module 60 is arranged coaxially with the second axis O2 and is formed in a cylindrical shape that surrounds the eccentric portion 11b. The external gear module 60 is supported on the eccentric portion 11b via a bearing 54 so as to be rotatable around the second axis O2. The external gear module 60 comprises a first external gear 61 and a second external gear 62. The first external gear 61 and the second external gear 62 are integrally formed as the external gear module 60. That is, each of the first external gear 61 and the second external gear 62 is provided so as to be rotatable as a single unit around the second axis O2. However, the first external gear 61 and the second external gear 62 may be made of separate components as long as they are configured to rotate as a single unit.

[0024] The first external gear 61 is formed in the portion of the external gear module 60 located on the first axial side. As shown in Figures 3 and 5, the first external teeth 65 are formed on the outer circumferential surface of the first external gear 61. Multiple first external teeth 65 are formed at intervals in the circumferential direction (second circumferential direction) around the second axis O2.

[0025] Figure 6 is a perspective view showing the first rotating body 10, the external gear module 60, the first internal gear 22, and the second internal gear 32. As shown in Figure 3, the second external gear 62 is formed in the external gear module 60 at a different axial position from the first external gear 61. The second external gear 62 is formed in the portion of the external gear module 60 located on the second axial side relative to the first external gear 61. As shown in Figures 3, 5, and 6, second external teeth 66 are formed on the outer circumferential surface of the second external gear 62. Multiple second external teeth 66 are formed at intervals in the second circumferential direction. In this embodiment, the second external gear 62 has a smaller diameter than the first external gear 61. The number of teeth on the second external gear 62 is set to be less than the number of teeth on the first external gear 61.

[0026] <Second Rotating Body 20> As shown in Figure 3, the second rotating body 20 is located on the first axial side of the power transmission device 1. When viewed from the axial direction, the second rotating body 20 is formed as a continuous annular shape over the entire circumference around the first axis O1. The second rotating body 20 surrounds the first axial side portion of the first rotating body 10 from the radial outside. The second rotating body 20 comprises a first extension portion 21 and a first internal gear 22.

[0027] The first extension portion 21 is formed in a cylindrical shape and is arranged coaxially with the first axis O1. The first extension portion 21 surrounds the portion of the main shaft portion 11a located on the first axial side of the balancer 11c from the radial outside. The first extension portion 21 has a flange portion 21a that extends radially outward at its second axial end. A bearing 51 is interposed between the first extension portion 21 and the main shaft portion 11a. Therefore, the first extension portion 21 is rotatable around the first axis O1 relative to the main shaft portion 11a. A bearing 56 is provided on the outside of the first extension portion 21. The bearing 56 is interposed between the first extension portion 21 and the fourth rotating body 40, supporting the first extension portion 21 and the fourth rotating body 40 so that they can rotate relative to each other around the first axis O1.

[0028] As shown in Figures 2 and 3, the first extension portion 21 has a second mounting portion (mounting portion) 25 to which an external member 102 can be attached. In this embodiment, the second mounting portion 25 is, for example, a plurality of bolt holes formed on the end face 21f of the first extension portion 21 facing the first side in the axial direction. The plurality of bolt holes as the second mounting portion 25 are provided at intervals in the first circumferential direction. The first extension portion 21 can be fitted with an external member 102 (see Figure 3) by attaching bolts (not shown) to each of the plurality of second mounting portions 25.

[0029] The first internal gear 22 is located on the second axial side of the flange portion 21a. Specifically, the first internal gear 22 is fixed to the flange portion 21a by bolts 24, with the first internal gear 22 overlapping the flange portion 21a in the axial direction. As shown in Figures 3 and 6, the first internal gear 22 is formed in an annular shape and is arranged coaxially with the first axis O1. The first internal gear 22 surrounds the first external gear 61 at a position where it overlaps with the first external gear 61 in the axial direction (a position where it overlaps when viewed from the radial direction). Multiple first internal teeth 23 are provided on the inner circumferential surface of the first internal gear 22. The multiple first internal teeth 23 are formed with spacing in the first circumferential direction. The multiple first internal teeth 23 of the first internal gear 22 mesh with the multiple first external teeth 65 of the first external gear 61. The number of teeth of the first external teeth 65 is set to be, for example, one less than the number of teeth of the first internal teeth 23.

[0030] <Third rotating body 30> As shown in Figure 3, the third rotating body 30 is positioned in the power transmission device 1 on the opposite side (second side in the axial direction) from the second rotating body 20 with respect to the external gear module 60. When viewed from the axial direction, the third rotating body 30 is formed as a continuous annular shape over the entire circumference around the first axis O1. The third rotating body 30 surrounds the second side portion in the axial direction of the first rotating body 10 from the radial outside. The third rotating body 30 comprises a second extension portion 31 and a second internal gear 32.

[0031] The second extension portion 31 is formed in a cylindrical shape coaxial with the first axis O1 and surrounds the second axial end of the main shaft portion 11a. A bearing 52 is interposed between the second extension portion 31 and the main shaft portion 11a. Therefore, the second extension portion 31 is rotatably mounted on the main shaft portion 11a around the first axis O1. A bearing 57 is provided on the outside of the second extension portion 31. The bearing 57 is interposed between the second extension portion 31 and the fourth rotating body 40, supporting the second extension portion 31 and the fourth rotating body 40 so that they can rotate relative to each other around the first axis O1.

[0032] As shown in Figure 3, the third rotating body 30 has a third mounting portion (mounting portion) 35 to which an external member 103 can be attached. As shown in Figures 1 and 3, in this embodiment, the third mounting portion 35 is, for example, a plurality of bolt holes formed on the end face 31f facing the second side in the axial direction of the second extension portion 31. The plurality of bolt holes as the mounting portion 35 are provided at intervals in the first circumferential direction. The external member 103 can be attached to the end face 31f using a plurality of bolts (not shown).

[0033] The second internal gear 32 is provided on the first axial side of the second extension 31. Specifically, the second internal gear 32 is fixed to the second extension 31 by bolts 34 in a state where it is axially superimposed on the outer circumference of the second extension 31. As shown in Figures 3 and 6, the second internal gear 32 is formed in an annular shape and is arranged coaxially with the first axis O1. The second internal gear 32 is provided at a position where it overlaps with the second external gear 62 in the axial direction (a position where they overlap when viewed from the radial direction). Multiple second internal teeth 33 are provided on the inner circumferential surface of the second internal gear 32. The multiple second internal teeth 33 are formed with spacing in the first circumferential direction. The multiple second internal teeth 33 of the second internal gear 32 mesh with the multiple second external teeth 66 of the second external gear 62. Here, the number of teeth of the first internal gear 22 and the number of teeth of the second internal gear 32 are different. In this embodiment, the second internal gear 32 has a smaller diameter than the first internal gear 22. The number of teeth of the second internal teeth 33 of the second internal gear 32 is set to be less than the number of teeth of the first internal teeth 23 of the first internal gear 22. Also, the number of teeth of the second external teeth 66 is set to be, for example, one less than the number of teeth of the second internal teeth 33.

[0034] In this embodiment, the first internal tooth 23 or the first external tooth 65 is formed based on a setting curve obtained by a trochoid curve (epitrochoid curve). In this embodiment, the second internal tooth 33 or the second external tooth 66 is formed based on a setting curve obtained by a trochoid curve. A trochoid curve is obtained by the trajectory traced by a drawing point set at an eccentric position from the center of a rolling circle when the rolling circle rolls without slipping on a reference circle having a predetermined radius. The setting curve is formed by the envelope of the group of arcs traced by a trajectory circle having a predetermined radius moving on the trochoid curve. However, the setting curve can be arbitrarily set regardless of the trochoid curve, taking tolerances into consideration.

[0035] <Fourth Rotation Body 40> As shown in Figure 3, the fourth rotating body 40 is positioned radially outward relative to the first rotating body 10, the second rotating body 20, and the third rotating body 30. The fourth rotating body 40 is formed in a cylindrical shape coaxial with the first axis O1 and surrounds the first rotating body 10, the second rotating body 20, and the third rotating body 30 from the radial outside. In other words, the fourth rotating body 40 forms the outer shell of the power transmission device 1 and functions as a housing that covers the first rotating body 10, the second rotating body 20, and the third rotating body 30 together from the radial outside. The fourth rotating body 40 comprises a rotating member 41, a first cylindrical portion 42, and a second cylindrical portion 43.

[0036] The rotating member 41 is provided in the axial direction between the first internal gear 22 and the second internal gear 32. The rotating member 41 is formed in an annular shape and is arranged coaxially with the first axis O1. When viewed from the axial direction, the rotating member 41 is provided so as to overlap with the outer circumference of the first external gear 61.

[0037] As shown in Figures 3 and 5, in this embodiment, the rotating member 41 is provided with a plurality of pins 44. The plurality of pins 44 are provided at intervals in the first circumferential direction. Each of the plurality of pins 44 is provided so as to protrude from the rotating member 41 to the first axial side. Each of the plurality of pins 44 is inserted into a plurality of pin insertion portions 68 formed in the first external gear 61. Each pin insertion portion 68 is provided at intervals in the second circumferential direction in the first external gear 61. Each pin insertion portion 68 has an inner diameter larger than the outer diameter of the pin 44. For example, when the first external gear 61 revolves around the first axis O1, the pin insertion portions 68 and the pins 44 come into contact, transmitting rotational force between the first external gear 61 and the rotating member 41, causing the rotating member 41 to rotate around the first axis O1. In other words, the rotating member 41 rotates around the first axis O1 in conjunction with the rotation of the first external gear 61.

[0038] As shown in Figure 3, the first cylindrical portion 42 is formed in a cylindrical shape extending from the outer circumference of the rotating member 41 to the first side in the axial direction. The first cylindrical portion 42 is connected to the rotating member 41 via a plurality of bolts 49 (see Figure 1). An inner circumferential flange portion 42k extending radially inward is formed at the first end of the first cylindrical portion 42 in the axial direction. A bearing 56 is interposed between the inner circumferential flange portion 42k and the first extension portion 21.

[0039] The second cylindrical portion 43 is formed as a cylindrical shape extending from the rotating member 41 to the second side in the axial direction. In this embodiment, the second cylindrical portion 43 is formed with a smaller diameter than the first cylindrical portion 42. However, the second cylindrical portion 43 may have the same diameter as the first cylindrical portion 42. A bearing 57 is interposed between the second cylindrical portion 43 and the second extended portion 31.

[0040] The fourth rotating body 40 has a fourth mounting portion (mounting portion) 45 to which an external member 104 can be attached. As shown in Figures 1 and 3, in this embodiment, the fourth mounting portion 45 is, for example, a plurality of bolt holes formed on the end face 43f of the second cylindrical portion 43 facing the second side in the axial direction. The plurality of bolt holes as the fourth mounting portion 45 are provided at intervals in the first circumferential direction. The external member 104 can be attached to the end face 43f using a plurality of bolts (not shown). The fourth mounting portion 45 may also be a plurality of bolt holes formed on the end face 42f of the first cylindrical portion 42 facing the first side in the axial direction.

[0041] In this embodiment, the first extension portion 21 extends from the first internal gear 22 to the first axial side. As a result, the end face 21f of the first extension portion 21 is flush with the end face 42f of the first cylindrical portion 42, or is located to the first axial side of the end face 42f. The second extension portion 31 extends from the second internal gear 32 to the second axial side. As a result, the end face 31f of the second extension portion 31 is flush with the end face 43f of the second cylindrical portion 43, or is located to the second axial side of the end face 43f. However, the end face 21f of the first extension portion 21 or the end face 31f of the second extension portion 31 may be located axially inward with respect to the fourth rotating body 40.

[0042] <Operation of power transmission device 1> In the power transmission device 1 of this embodiment, for example, when the first rotating body 10 rotates around the first axis O1, the eccentric portion 11b revolves (eccentrically rotates) around the first axis O1. That is, the second axis O2 revolves around the first axis O1. While the second axis O2 completes one rotation around the first axis O1, the external gear module 60 rotates (rotates) around the second axis O2 such that the first external teeth 65 overcome the first internal teeth 23 one by one, and the second external teeth 66 overcome the second internal teeth 33 one by one. As the first external gear 61 rotates, the second rotating body 20, which has the first internal gear 22 that meshes with the first external gear 61, rotates around the first axis O1. Also, as the second external gear 62 rotates, the third rotating body 30, which has the second internal gear 32 that meshes with the second external gear 62, rotates around the first axis O1. In this way, torque (rotational force) is transmitted between the first rotating body 10, the second rotating body 20, the third rotating body 30, and the fourth rotating body 40 in the power transmission device 1. Here, torque is transmitted between the first rotating body 10 and the second rotating body 20, and between the first rotating body 10 and the third rotating body 30, with the speed being reduced or increased.

[0043] <Installation configuration of power transmission device 1> As described above, in the power transmission device 1, the first rotating body 10, the second rotating body 20, the third rotating body 30, and the fourth rotating body 40 can be attached to external members 101 to 104 via mounting parts 14, 25, 35, and 45. One of the first rotating body 10, the second rotating body 20, the third rotating body 30, and the fourth rotating body 40 can be fixed to a fixed mounting object such as the main body of an industrial machine. Another one of the other four rotating bodies 10, 20, 30, and 40 can be connected to the input drive shaft of a motor or the like that rotates the first rotating body 10, 20, 30, and 40. The remaining two of the four rotating bodies 10, 20, 30, and 40 can each be connected to a first drive object and a second drive object on the output side, such as the stirring mechanism of an industrial machine.

[0044] Figure 7 shows an example of the installation configuration of the power transmission device 1. In Figure 7, (1) to (11) show multiple installation configurations of the power transmission device 1. The upper section shows the mounting locations of the first rotating body 10, the second rotating body 20, the third rotating body 30, and the fourth rotating body 40, while the lower section shows the rotational direction relative to the drive shaft and whether the rotational speed relative to the drive shaft is decelerating, increasing, or constant.

[0045] For example, as shown in Figure 7(1), the first rotating body 10 may be connected to the drive shaft as an external member 101 via the first mounting portion 14, and the second rotating body 20 may be fixed to the object to be mounted as an external member 102 via the second mounting portion 25. In this case, the third rotating body 30 is connected to the first drive object as an external member 103 via the third mounting portion 35, and the fourth rotating body 40 is connected to the second drive object as an external member 104 via the fourth mounting portion 45. In this case, if the rotation direction of the first rotating body 10, which is rotationally driven by the drive shaft, is forward, the third rotating body 30 rotates in reverse and decelerates to drive the first drive object, and the fourth rotating body 40 rotates in forward and decelerates to drive the second drive object.

[0046] Alternatively, as shown in (5) of Figure 7, for example, the second rotating body 20 may be connected to the drive shaft and the third rotating body 30 may be fixed to the object to be mounted. In this case, the first rotating body 10 is connected to the first object to be driven, and the fourth rotating body 40 is connected to the second object to be driven. In this case, if the rotation direction of the second rotating body 20, which is rotationally driven by the drive shaft, is set to forward rotation, the first rotating body 10 rotates forward while increasing speed to rotate the first object to be driven, and the fourth rotating body 40 rotates forward while increasing speed to rotate the second object to be driven.

[0047] Alternatively, as shown in Figure 7(8), for example, the third rotating body 30 may be connected to the drive shaft and the fourth rotating body 40 may be fixed to the object to be mounted. In this case, the first rotating body 10 is connected to the first object to be driven, and the second rotating body 20 is connected to the second object to be driven. In this case, if the rotation direction of the third rotating body 30, which is rotationally driven by the drive shaft, is set to forward rotation, the first rotating body 10 rotates in reverse while increasing speed to drive the first object to be driven, and the second rotating body 20 rotates in forward rotation while decreasing speed to drive the second object to be driven.

[0048] Alternatively, as shown in Figure 7(9), for example, the fourth rotating body 40 may be connected to the drive shaft and the first rotating body 10 may be fixed to the object to be mounted. In this case, the second rotating body 20 is connected to the first object to be driven, and the third rotating body 30 is connected to the second object to be driven. In this case, if the rotation direction of the fourth rotating body 40, which is rotationally driven by the drive shaft, is set to forward rotation, the second rotating body 20 and the third rotating body 30 rotate in the forward direction and rotate the first object to be driven at a constant speed.

[0049] Thus, in this embodiment, the power transmission device 1 comprises a first rotating body 10 having a main shaft portion 11a and an eccentric portion 11b; a second rotating body 20 having a first external gear 61 and a second external gear 62 provided radially outward from the eccentric portion 11b around the first axis O1, a first internal gear 22 that meshes with the first external gear 61; a third rotating body 30 having a second internal gear 32 that meshes with the second external gear 62; and a fourth rotating body 40 having a rotating member 41 that rotates around the first axis O1 in conjunction with the rotation of the first external gear 61. In this configuration, the power transmission device 1 can transmit rotation between the first rotating body 10 and the second rotating body 20, third rotating body 30, and fourth rotating body 40 via an eccentric portion 11b provided on the first rotating body 10. Since the second rotating body 20 and the third rotating body 30 are rotatable around the first axis O1, there is no need to use multiple sets of planetary gear mechanisms. As a result, the number of parts can be reduced, and costs and assembly man-hours can be lowered.

[0050] In this embodiment, one of the first rotating body 10, the second rotating body 20, the third rotating body 30, and the fourth rotating body 40 can be fixed to the object to be mounted, one of the other two of the first rotating body 10, the second rotating body 20, the third rotating body 30, and the fourth rotating body 40 can be connected to the drive shaft, and each of the remaining two of the first rotating body 10, the second rotating body 20, the third rotating body 30, and the fourth rotating body 40 can be connected to the object to be driven. With this configuration, the first rotating body 10, the second rotating body 20, the third rotating body 30, and the fourth rotating body 40 can be appropriately connected to the mounting object, the drive shaft, and the driven object. This allows the power transmission device 1 to be used in various ways, increasing its versatility.

[0051] In this embodiment, the second rotating body 20 has a first extended portion 21, and the third rotating body 30 has a second extended portion 31. With this configuration, regardless of the meshing position between the first external gear 61 and the first internal gear 22, and the meshing position between the second external gear 62 and the second internal gear 32, external members 102 and 103 can be attached to the second rotating body 20 and the third rotating body 30, respectively, via the first extension portion 21 and the second extension portion 31.

[0052] In this embodiment, the second rotating body 20, the third rotating body 30, and the fourth rotating body 40 are each formed radially outward from the first rotating body 10, surrounding the first rotating body 10. With this configuration, the second rotating body 20, the third rotating body 30, and the fourth rotating body 40 can each be formed in an annular or cylindrical shape so as to surround the first rotating body 10. Compared to, for example, a configuration using multiple sets of planetary gear mechanisms, this method suppresses the increase in the number of parts and allows for miniaturization in the radial direction.

[0053] In this embodiment, the fourth rotating body 40 is configured as a housing that covers the first rotating body 10, the second rotating body 20, and the third rotating body 30 from the radial outside. With this configuration, the fourth rotating body 40 also serves as the housing, allowing the power transmission device 1 to be constructed with fewer parts.

[0054] In this embodiment, the number of teeth of the first external gear 61 is less than the number of teeth of the first internal gear 22, and the number of teeth of the second external gear 62 is less than the number of teeth of the second internal gear 32. With this configuration, the speed can be changed between the first rotating body 10, the second rotating body 20, and the third rotating body 30 by the difference in the number of teeth between the first external gear 61 and the second internal gear 32, and between the second external gear 62 and the second internal gear 32.

[0055] In this embodiment, the number of teeth of the first internal gear 22 is configured to be different from the number of teeth of the second internal gear 32. This configuration allows for different gear ratios between the second rotating body 20 and the third rotating body 30.

[0056] In this embodiment, one of the first external gear 61 and the rotating member 41 is equipped with a pin 44, while the other member has a pin insertion portion 68. With this configuration, the pin insertion portion 68 and the pin 44 inserted into the pin insertion portion 68 can transmit rotation between the first external gear 61, which revolves around the first axis O1, and the rotating member 41 of the fourth rotating body 40, thereby allowing the first rotating body and the second rotating body to rotate at a predetermined speed ratio.

[0057] In this embodiment, the rotating member 41 is connected to the first external gear 61 between the first internal gear 22 and the second internal gear 32. This configuration makes it possible to miniaturize the power transmission device 1 in the axial direction.

[0058] While preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to these embodiments. Additions, omissions, substitutions, and other modifications are permitted without departing from the spirit of the present disclosure. The present disclosure is not limited by the above description, but only by the appended claims. For example, in the embodiment described above, a configuration was described in which one of the first internal teeth 23, the second internal teeth 33, and the first external teeth 65, the second external teeth 66 is formed along a set curve obtained by a trochoid curve, but the configuration is not limited to this. It is sufficient that at least one of the first internal teeth 23, the second internal teeth 33, and the first external teeth 65, the second external teeth 66 is formed along a set curve.

[0059] In the embodiment described above, the fourth rotating body 40 is configured as a housing that covers the first rotating body 10, the second rotating body 20, and the third rotating body 30 from the radial outside, but the configuration is not limited to this. The fourth rotating body 40 may not be a housing, and the power transmission device 1 may separately include a housing that covers the first rotating body 10, the second rotating body 20, the third rotating body 30, and the fourth rotating body 40 from the radial outside.

[0060] In the embodiments described above, a configuration was described in which the internal gear and external gear have two stages in the axial direction, but the configuration is not limited to this. The internal gear and external gear may have one stage, or three or more stages.

[0061] In the embodiment described above, the number of teeth of the second external gear 62 is set to be less than the number of teeth of the first external gear 61, but the configuration is not limited to this. The number of teeth of the second external gear 62 may be set to be more than the number of teeth of the first external gear 61.

[0062] In the embodiment described above, the number of teeth of the second internal teeth 33 of the second internal gear 32 is set to be less than the number of teeth of the first internal teeth 23 of the first internal gear 22, but the configuration is not limited to this. The number of teeth of the second internal teeth 33 of the second internal gear 32 may be set to be more than the number of teeth of the first internal teeth 23 of the first internal gear 22.

[0063] In the embodiment described above, the number of teeth of the first internal gear 22 is different from the number of teeth of the second internal gear 32, but the embodiment is not limited to this configuration. The number of teeth of the first internal gear 22 may be the same as the number of teeth of the second internal gear 32.

[0064] In the embodiment described above, the number of teeth of the first external gear 61 is less than the number of teeth of the first internal gear 22, but the configuration is not limited to this. The number of teeth of the first external gear 61 may be greater than the number of teeth of the first internal gear 22.

[0065] In the embodiment described above, the number of teeth of the second external gear 62 is less than the number of teeth of the second internal gear 32, but the configuration is not limited to this. The number of teeth of the second external gear 62 may be greater than the number of teeth of the second internal gear 32.

[0066] In the embodiment described above, the first external gear 61 and the rotating member 41 are configured to transmit rotation between the first external gear 61 and the rotating member 41 via a pin 44 and a pin insertion portion 68, but the configuration is not limited to this. Any other configuration can be adopted as appropriate, as long as rotation can be transmitted between the first external gear 61 and the rotating member 41.

[0067] Furthermore, it is possible to replace the components in the embodiments described above with well-known components as appropriate, without departing from the spirit of this disclosure, and the modifications described above may be combined as appropriate. [Explanation of Symbols]

[0068] 1. Power transmission device 10 First Rotating Body 11a Main shaft 11b Eccentric part 14. First mounting section (mounting section) 20 Second Rotating Body 21 First extension section 22 First internal gear 23 First internal tooth 25 Second mounting section (mounting section) 30 Third Rotation Body 31 Second extension section 32 Second internal gear 33 Second Inner Teeth 35 Third mounting section (mounting section) 40 Fourth rotation body 41 Rotating member 44 pins 45. Fourth mounting section (mounting section) 61 First external gear 62 Second external gear 65 First external tooth 66 Second external tooth 68 Pin insertion section 101-104 External components

Claims

1. A first rotating body having a main shaft portion extending axially along a first axis and rotatably mounted around the first axis, and an eccentric portion formed around a second axis eccentric to the first axis and eccentric to the main shaft portion, A first external gear is provided in the eccentric portion and is rotatably mounted around the second axis in conjunction with the rotation of the first rotating body, A second external gear is provided on the eccentric portion at a different position in the axial direction relative to the first external gear, and is rotatable around the second axis as the first rotating body rotates, A second rotating body is provided on the main body shaft so as to be rotatable around the first axis and has a first internal gear that meshes with the first external gear, A third rotating body is provided on the main shaft portion so as to be rotatable around the first axis and has a second internal gear that meshes with the second external gear, The system comprises a fourth rotating body positioned radially outward from the first rotating body, the second rotating body, and the third rotating body, intersecting the first axis, and having a rotating member that rotates around the first axis in conjunction with the rotation of the first external gear. Power transmission device.

2. Each of the first rotating body, the second rotating body, the third rotating body, and the fourth rotating body has a mounting portion to which an external member can be attached. Any one of the first rotating body, the second rotating body, the third rotating body, and the fourth rotating body can be fixed to the object to be attached as an external member via the mounting portion of any one of the aforementioned rotating bodies. Any other of the first rotating body, the second rotating body, the third rotating body, and the fourth rotating body is connected as an external member to a drive shaft that rotates the first rotating body, the second rotating body, the third rotating body, and the fourth rotating body via the mounting portion of any other of the other members. Each of the remaining two of the first, second, third, and fourth rotating bodies is connectable to the two external drive objects via the mounting portion of each of the remaining two bodies. The power transmission device according to claim 1.

3. The second rotating body extends to the first side in the axial direction relative to the first internal gear and has a first extension portion on which the mounting portion is formed. The third rotating body extends to the second axial side relative to the second internal gear and has a second extension portion on which the mounting portion is formed. The power transmission device according to claim 2.

4. Each of the second, third, and fourth rotating bodies is formed to surround the first rotating body, on the radially outward side of the first rotating body. The power transmission device according to claim 1 or 2.

5. The fourth rotating body is a housing that covers the first rotating body, the second rotating body, and the third rotating body from the radially outer side. The power transmission device according to claim 1 or 2.

6. The number of teeth of the first external gear is less than the number of teeth of the first internal gear. The number of teeth on the second external gear is less than the number of teeth on the second internal gear. The power transmission device according to claim 1 or 2.

7. The number of teeth of the first internal gear is different from the number of teeth of the second internal gear. The power transmission device according to claim 5.

8. The first external gear and one of the rotating members are provided with a pin that protrudes toward the first external gear and the other of the rotating members. The other member has an inner diameter larger than the outer diameter of the pin and has a pin insertion portion into which the pin is inserted. The power transmission device according to claim 1 or 2.

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