Planetary gear mechanism and planetary gear system equipped with said planetary gear mechanism

Abstract

The present invention provides a planetary gear mechanism and a planetary gear device equipped with the present invention, which allows for the replacement of only two components, the sun gear and the bearing, and furthermore, simplifies the assembly of the two components. [Solution] The planetary gear mechanism M1 comprises a sun gear 2 with a rotating shaft 20, a carrier 4, a bearing B1, and a C-ring 9. The carrier 4 includes an insertion passage R4 into which the sun gear 2 and the rotating shaft 20 can be inserted together with the bearing B1, and a housing space S4 capable of accommodating the sun gear 2. The bearing B1 has an outer diameter larger than the tip circle diameter of the sun gear 2 and is interlock-fitted to the outer circumferential surface of the rotating shaft 20, while being clearance-fitted to the inner circumferential surface of the insertion passage R4. The C-ring 9 prevents the bearing B1 from coming off by fitting into the fitting groove 4g.

Description

Technical Field

[0001] The present invention relates to a planetary gear mechanism and a planetary gear device provided with the planetary gear mechanism.

Background Art

[0002] A planetary gear mechanism includes a sun gear, a carrier having planetary gears, and an internal gear on the same axis, and is used as, for example, a speed change mechanism for increasing or decreasing the rotation of a power source (drive source).

[0003] In recent years, as a geared motor combined with a motor, for example, the need for a speed change mechanism has been increasing because it is mounted on a robot arm, an AGV (Automated Guided Vehicle), etc.

[0004] On the other hand, the planetary gear mechanism employed in a geared motor is required to have a thin and flat structure (a thin and flat structure) in the axial direction in consideration of the effectiveness in terms of strength. A planetary gear mechanism with a thin and flat structure can shorten its axial length (axial direction length) with respect to the outer diameter of the planetary gear mechanism and is effective in terms of strength.

[0005] Among planetary gear mechanisms, a 3K type planetary gear mechanism (bilateral gear) includes a compound planetary gear in which two different gears are integrated in two stages on the same axis (see, for example, Non-Patent Document 1). The 3K type planetary gear mechanism is effective in making it thin and flat because the number of parts arranged in the axial direction is reduced in that one sun gear (a part) can rotate the planetary gears in two stages.

[0006] However, in a 3K-type planetary gear mechanism, the sun gear, due to its characteristic of receiving rotational input from the power source, is a component that rotates at the same rotational speed as the power source and meshes with multiple planetary gears. For this reason, in a 3K-type planetary gear mechanism, the sun gear and the bearing attached to its rotation axis tend to wear significantly more than other components of the 3K-type planetary gear mechanism. Furthermore, in a 3K-type planetary gear mechanism, if the sun gear is not positioned correctly, for example, if the sun gear is misaligned relative to the axial direction, this misalignment can cause the two-stage composite planetary gear to tilt, thus reducing output efficiency.

[0007] In contrast, a known method for preventing wear and positioning related to planetary gear mechanisms is a geared motor in which the connection between the input element of the planetary gear reducer and the power source (or connecting part) is in a spigot structure (see, for example, Patent Document 1). This geared motor suppresses misalignment of the sun gear and its bearing by providing a fitting hole at the end of the input shaft of the planetary gear reducer, fitting the output shaft of the power source into the fitting hole, and connecting the planetary gear reducer and the motor with an intermediate part (input shaft box).

[0008] However, the structure described in Patent Document 1 primarily involves replacing the entire planetary gear reducer even when only two components—the sun gear and the bearing attached to the sun gear's rotating shaft—are worn. Therefore, repairing the sun gear and its bearing using the structure described in Patent Document 1 is more costly than replacing only the worn-out components (i.e., the sun gear and its bearing). Furthermore, the axial position of the sun gear and its bearing depends on the mounting accuracy of the power source connected to the sun gear's rotating shaft, and the intermediate components connecting the power source to the rotating shaft. Depending on the degree of mounting accuracy, this can cause misalignment. This ultimately leads to wear on both the sun gear and its bearing. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 05-300695 [Overview of the project] [Problems that the invention aims to solve]

[0010] The object of the present invention is to provide a planetary gear mechanism and a planetary gear device equipped with the present invention, which allows for the replacement of only two components, a sun gear and a bearing disposed between the rotating shaft of the sun gear and the carrier, and furthermore, which simplifies the assembly of the two components. [Means for solving the problem]

[0011] (1) The planetary gear mechanism according to the present invention comprises a sun gear having a rotating shaft, a carrier having planetary gears, a bearing that rotatably supports the rotating shaft and the carrier, and a C-ring that is detachable from the rotating shaft or the carrier, wherein the carrier comprises an insertion passage into which the sun gear and the rotating shaft connected to the sun gear can be inserted axially together with the bearing, and a housing space connected to the insertion passage and capable of housing the sun gear, wherein the bearing has an outer diameter larger than the tip circle diameter of the sun gear and is interlock-fitted to the outer circumferential surface of the rotating shaft, while being clearance-fitted to the inner circumferential surface of the carrier that forms the insertion passage of the carrier, and the C-ring is fitted into a fitting groove formed on one side in the axial direction near the input / output end of the rotating shaft, either on the inner circumferential surface of the carrier or the outer circumferential surface of the rotating shaft, thereby preventing the bearing from coming off from that side in the axial direction.

[0012] (2) In the planetary gear mechanism described in (1) above, it is preferable that the rotating shaft has a stepped surface on the other side in the axial direction of the outer circumferential surface of the rotating shaft that is closer to the sun gear, for positioning the bearing on the other side in the axial direction, and the carrier has a stepped surface on the other side in the axial direction of the inner circumferential surface of the carrier that is for positioning the bearing.

[0013] (3) The planetary gear mechanism described in (1) or (2) above further comprises an internal gear element having an internal gear that meshes with the planetary gear, and a second bearing that rotatably supports the internal gear element and the carrier, wherein the internal gear element has a through passage at one end of the internal gear element in the axial direction, which penetrates the one end of the internal gear element in the axial direction and where the one end of the carrier in the axial direction is positioned, and the second bearing can rotatably support the one end of the carrier in the axial direction and the one end of the internal gear element in the axial direction within the through passage.

[0014] (4) In any one of the planetary gear mechanisms described in (1) to (3) above, the planetary gear may be a composite planetary gear comprising a first planetary gear that meshes with the sun gear and a second planetary gear that is integrally provided with the first planetary gear.

[0015] (5) The planetary gear mechanism described in (4) above preferably further comprises a second internal gear element that meshes with the second planetary gear, a third bearing that rotatably supports the internal gear element and the second internal gear element, and a fourth bearing that rotatably supports the carrier and the second internal gear element.

[0016] (6) The planetary gear device according to the present invention comprises a planetary gear mechanism as described in any one of (1) to (5) above. [Effects of the Invention]

[0017] According to the present invention, it is possible to select to replace only two components, the sun gear and the bearing disposed between the rotating shaft of the sun gear and the carrier, and furthermore, it is possible to provide a planetary gear mechanism and a planetary gear device equipped with the present invention, in which the assembly of the two components is simplified. [Brief explanation of the drawing]

[0018] [Figure 1]It is a side view showing a planetary gear device provided with a planetary gear mechanism according to a first embodiment of the present invention. [Figure 2] It is a front view showing the planetary gear device of FIG. 1 from the input side when the planetary gear device of FIG. 1 is used as a speed reduction device. [Figure 3] It is a rear view showing the planetary gear device of FIG. 1 from the output side when the planetary gear device of FIG. 1 is used as a speed reduction device. [Figure 4] It is a cross-sectional view showing the planetary gear device of FIG. 3 in an X-X cross-section. [Figure 5] It is an enlarged cross-sectional view showing a state in which a part of region Y in FIG. 4 is omitted. [Figure 6] It is a perspective view showing the planetary gear device of FIG. 2. [Figure 7] It is a perspective view showing a C-ring removed from the planetary gear device of FIG. 6. [Figure 8] It is a perspective view showing a state in which the C-ring of FIG. 7 is removed from the planetary gear device of FIG. 6. [Figure 9] It is a perspective view showing a state in which the sun gear unit related to the planetary gear mechanism of the planetary gear device of FIG. 8 is removed from the planetary gear device of FIG. 8. [Figure 10] It is a perspective view showing the sun gear unit removed from the planetary gear device of FIG. 8. [Figure 11] It is a perspective view showing a bearing removed from the sun gear unit of FIG. 10. [Figure 12] It is a perspective view showing a sun gear provided with a rotating shaft from which the bearing of FIG. 11 is removed from the sun gear unit of FIG. 10.

Embodiments for Carrying Out the Invention

[0019] Hereinafter, with reference to the drawings, a planetary gear mechanism and a planetary gear device provided with the planetary gear mechanism according to an embodiment of the present invention will be described.

[0020] Here, "axial direction" refers to the direction in which the axis (central axis) extends. In particular, when a planetary gear mechanism (planetary gear device) is used as a reduction mechanism (reduction device), the input side of the planetary gear mechanism (planetary gear device) corresponds to one side of the axial direction, and the output side of the planetary gear mechanism (planetary gear device) corresponds to the other side of the axial direction. Furthermore, "circumferential direction" refers to the circumferential direction around the axis. Furthermore, "perpendicular direction" refers to the direction perpendicular to the axial direction. In addition, "perpendicular direction" is also called the "radial direction" when the axis is taken as the reference (center). In particular, when referring to the radial direction, the side closer to the axis is called the "inner radial direction," and the side farther from the axis is called the "outer radial direction."

[0021] Figure 1 shows a planetary gear system 1A according to a first embodiment of the present invention, viewed from the side. The planetary gear system 1A includes a planetary gear mechanism M1 according to a first embodiment of the present invention. Figure 2 shows the planetary gear system 1A from the input side when it is used as a reduction gear. Figure 3 shows the planetary gear system 1A from the output side when it is used as a reduction gear.

[0022] Furthermore, Figure 4 shows the planetary gear unit 1A in the XX cross-section of Figure 3. Here, the XX cross-section is a cross-section viewed in a plane that includes the central axis O of the planetary gear unit 1A (hereinafter simply referred to as "axis O"). Note that Figure 4 shows the cross-sectional shape of the planetary gear unit 1A with the XX cross-section of Figure 3 turned vertically.

[0023] The planetary gear system 1A according to this embodiment is a so-called 3K type planetary gear system. The planetary gear system 1A according to this embodiment includes a planetary gear mechanism M1. In this embodiment, the planetary gear mechanism M1 includes a sun gear 2 having a rotating shaft 20, a carrier 4 having a plurality of compound planetary gears 3, a first bearing (bearing) B1 that rotatably supports the rotating shaft 20 and the carrier 4, and a C-ring 9 that can be attached to or detached from the rotating shaft 20 or the carrier 4.

[0024] In addition, the planetary gear mechanism M1 is equipped with multiple carrier pins 5 corresponding to individual compound planetary gears 3. The compound planetary gears 3 are rotatably supported on a carrier 4 via the carrier pins 5. Furthermore, the planetary gear mechanism M1 is equipped with an internal toothed fixed gear element (internal toothed gear element) 7 that functions as a fixed gear, and an internal toothed rotating gear element (second internal toothed gear element) 6 that functions as a rotating gear.

[0025] In the following description, the planetary gear mechanism M1 is equipped with a composite planetary gear 3 as a two-stage gear, and is used as a reduction gear with the internal rotating gear element 6 as the output rotating element, by using the sun gear 2 as the input rotating element and the internal rotating gear element 7 as the fixed element. In the planetary gear mechanism M1, and by extension the planetary gear device 1A, the central axis of the sun gear 2 and the central axis of the internal rotating gear element 6 are both the same as axis O.

[0026] In the planetary gear mechanism M1, the sun gear 2 is an external gear equipped with external teeth 2a. A rotating shaft 20 is connected to the sun gear 2. In this embodiment, the rotating shaft 20 is formed integrally with the sun gear 2, but it can also be assembled as a separate component from the sun gear 2. In this embodiment, the central axis of the rotating shaft 20 is also the same as axis O, along with the central axis of the sun gear 2. For example, the rotation of a motor (not shown) as a power source is input to the rotating shaft 20. As a result, the rotation from the power source is input to the sun gear 2 via the rotating shaft 20.

[0027] The first bearing B1 is an annular bearing. In this embodiment, the first bearing B1 is a rolling bearing. In this embodiment, the first bearing B1 comprises an outer ring 31, an inner ring 32, and rolling elements 33 that are rotatable between the outer ring 31 and the inner ring 32. In this embodiment, the first bearing B1 is a ball bearing in which the rolling elements 33 are balls. However, the first bearing B1 may be a roller bearing in which the rolling elements 33 are rollers. Furthermore, the first bearing B1 may further comprise a cage that rotatably holds the rolling elements 33. In addition, at least one of the outer ring 31 and the inner ring 32 can be omitted. Also, the first bearing B1 may be a sliding bearing.

[0028] The carrier 4 has two pin support portions: an input-side pin support portion 4a and an output-side pin support portion 4b. The input-side pin support portion 4a and the output-side pin support portion 4b are spaced apart in the axial direction. The input-side end 5a of the carrier pin 5 is fixed to the input-side pin support portion 4a by being press-fitted into the input-side pin support portion 4a. In contrast, in this embodiment, the output-side end 5b of the carrier pin 5 is fixed to the output-side pin support portion 4b by being press-fitted into the output-side pin support portion 4b. Therefore, the carrier pin 5 is firmly fixed to the carrier 4 by both the input-side pin support portion 4a and the output-side pin support portion 4b.

[0029] Furthermore, in this embodiment, the input-side end (one end in the axial direction) of the carrier 4 is a cylindrical wall 4d. In this embodiment, the cylindrical wall 4d extends from the input-side pin support portion 4a toward the input side. In this embodiment, the cylindrical wall 4d is a cylindrical wall formed in an annular shape around the entire circumference of the axis O.

[0030] In this embodiment, the first bearing B1 is positioned between the rotating shaft 20 of the sun gear 2 and the input end of the carrier 4. In this embodiment, the first bearing B1 rotatably supports the carrier 4 and the sun gear 2 by rotatably supporting the cylindrical wall 4d of the carrier 4 and the rotating shaft 20 in the radial direction.

[0031] In this embodiment, the sun gear 2 is housed inside the carrier 4 together with the rotating shaft 20.

[0032] Figure 5 shows region Y in Figure 4. Figure 5 shows the sun gear 2, rotating shaft 20, first bearing B1, C-ring 9, and carrier 4. However, the compound planetary gear 3, carrier pin 5, and the third bearing B3 (described later) are omitted in Figure 5.

[0033] As shown in Figure 5, the sun gear 2 includes a rotating shaft 20. In this embodiment, the rotating shaft 20 includes an input-side rotating shaft portion 21 located on the input side and an output-side rotating shaft portion 22 located on the output side. In this embodiment, the input-side rotating shaft portion 21 and the output-side rotating shaft portion 22 are integrally formed. Furthermore, in this embodiment, the output-side rotating shaft portion 22 of the rotating shaft 20 is integrally formed with the sun gear 2. When the sun gear 2 and the rotating shaft 20 are integrally formed as in this embodiment, assembly errors can be suppressed. However, the sun gear 2 and the rotating shaft 20 can be assembled as separate parts, for example, by using a spline fitting.

[0034] In this embodiment, the outer circumferential surface F2 of the rotating shaft 20 comprises an input-side outer circumferential surface F21, an output-side outer circumferential surface F22, and a stepped surface F23 facing the input side. In this embodiment, the input-side outer circumferential surface F21 is formed by the outer circumferential surface of the input-side rotating shaft portion 21. Also in this embodiment, the output-side outer circumferential surface F22 is formed by the outer circumferential surface of the output-side rotating shaft portion 22. Furthermore, in this embodiment, the stepped surface F23 is connected to both the input-side outer circumferential surface F21 and the output-side outer circumferential surface F22. In this embodiment, the outer diameter D22 of the output-side rotating shaft portion 22 is larger than the outer diameter D21 of the input-side rotating shaft portion 21. As a result, a stepped surface F23 facing the input side is formed between the input-side rotating shaft portion 21 and the output-side rotating shaft portion 22 of the rotating shaft 20.

[0035] The carrier 4 includes an insertion passage R4 into which the sun gear 2 and the rotating shaft 20 connected to the sun gear 2 can be inserted axially together with the first bearing B1, and a housing space S4 connected to the insertion passage R4 and capable of accommodating the sun gear 2.

[0036] In this embodiment, the input-side pin support portion 4a and the output-side pin support portion 4b are connected by a connecting wall 4c. The carrier 4 has a plurality of connecting walls 4c arranged at circumferential intervals around the axis O. Between the connecting walls 4c, there are openings A4 that expose a portion of the composite planetary gear 3. In this embodiment, the external teeth (3c1, 3c2) of the composite planetary gear 3 are exposed to the outside through the openings A4 of the carrier 4. In this embodiment, the housing space S4 is an internal space partitioned by the output-side end 4e2 of the input-side pin support portion 4a, the input-side end 4e3 of the output-side pin support portion 4b, and the radially inner surface F44 of the connecting wall 4c.

[0037] On the other hand, in this embodiment, the insertion passage R4 opens at the input end 4e1 of the carrier 4 and penetrates axially to the accommodating space S4 of the carrier 4. In this embodiment, the insertion passage R4 comprises an input-side insertion passage portion R41 located on the input side and an output-side insertion passage portion R42 located on the output side. In this embodiment, the insertion passage R4 penetrates axially through the input-side portion (cylinder wall 4d and input-side pin support portion 4a) of the carrier 4 by having the input-side insertion passage portion R41 connect to the output-side insertion passage portion R42.

[0038] More specifically, in this embodiment, the input end 4e1 of the carrier 4 is the input end of the cylindrical wall 4d. In this embodiment, the insertion passage R4 has an input-side opening A41 formed at the input end 4e1 of the carrier 4 and an output-side opening A42 formed at the output end 4e2 of the input-side pin support portion 4a. In this embodiment, the input-side insertion passage portion R41 of the insertion passage R4 is open to the outside through the input-side opening A41. In contrast, in this embodiment, the output-side insertion passage portion R42 of the insertion passage R4 is open to the housing space S4 through the output-side opening A42. Thus, in this embodiment, the insertion passage R4 penetrates axially through the interior of the input-side portion of the carrier 4 (cylindrical wall 4d and input-side pin support portion 4a) so as to exit from the input end 4e1 of the carrier 4 to the housing space S4.

[0039] In this embodiment, the inner circumferential surface F4 of the carrier 4 that forms the insertion path R4 of the carrier 4 (hereinafter also referred to as the "insertion path inner circumferential surface of the carrier 4") comprises the input-side insertion path portion inner circumferential surface F41 of the carrier 4 that forms the input-side insertion path portion R41, and the output-side insertion path portion inner circumferential surface F42 of the carrier 4 that forms the output-side insertion path portion R42. Furthermore, in this embodiment, the insertion path inner circumferential surface F4 of the carrier 4 includes a stepped surface F43 that faces the input side. In this embodiment, the stepped surface F43 is connected to both the input-side insertion path portion inner circumferential surface F41 and the output-side insertion path portion inner circumferential surface F42. In this embodiment, the inner diameter D42 of the output-side insertion path portion R42 (diameter of the output-side opening A42) is smaller than the inner diameter D41 of the input-side insertion path portion R41 (diameter of the input-side opening A41). As a result, a stepped surface F43 oriented towards the input side is formed between the input-side insertion path portion R41 and the output-side insertion path portion R42 of the insertion path R4.

[0040] In this embodiment, the inner diameter D41 of the input-side insertion passage portion R41 of the insertion passage R4 formed in the carrier 4 is larger than the inner diameter D42 of the output-side insertion passage portion R42 of the insertion passage R4. This allows the insertion passage R4 to be configured to allow the first bearing B1, which is attached to the rotating shaft 20 of the sun gear 2, to be placed inside the insertion passage R4 through the input-side opening A41 of the insertion passage R4.

[0041] Furthermore, in this embodiment, the inner diameter D42 of the output-side insertion passage portion R42 of the insertion passage R4 formed in the carrier 4 is larger than the tip circle diameter D2 of the sun gear 2. In other words, the tip circle diameter D2 of the sun gear 2 is smaller than the inner diameter D42 of the output-side insertion passage portion R42 of the insertion passage R4. As a result, the sun gear 2 inserted into the insertion passage R4 can be further inserted into the housing space S4 of the carrier 4 through the output-side opening A42 of the insertion passage R4.

[0042] On the other hand, the first bearing B1 has an outer diameter D3 that is larger than the tip circle diameter D2 of the sun gear 2. In this embodiment, the outer diameter D3 of the first bearing B1 is the outer diameter of the outer ring 31. Therefore, in this embodiment, the outer ring 31 of the first bearing B1 has an outer diameter D3 that is larger than the tip circle diameter D2 of the sun gear 2.

[0043] Furthermore, the first bearing B1 is fitted tightly to the outer circumferential surface F2 of the rotating shaft 20, while being fitted with clearance to the inner circumferential surface F4 of the insertion passage of the carrier 4.

[0044] In this embodiment, the inner circumference of the first bearing B1 is interlocked with the input side rotating shaft portion 21 of the rotating shaft 20. In this embodiment, the inner circumference of the first bearing B1 is the inner ring 32. That is, in this embodiment, the inner ring 32 of the first bearing B1 is interlocked with the input side rotating shaft portion 21 of the rotating shaft 20. More specifically, in this embodiment, the inner surface of the inner ring 32 is interlocked with the input side outer surface F21 of the outer surface F2 of the rotating shaft 20. Therefore, the sun gear 2, the rotating shaft 20, and the first bearing B1 can be assembled into a single sun gear unit U by pre-attaching the first bearing B1 to the rotating shaft 20 of the sun gear 2.

[0045] In contrast, in this embodiment, the outer circumference of the first bearing B1 is clearance-fitted to the input side portion (cylinder wall 4d and input side pin support portion 4a) of the carrier 4. In this embodiment, the first bearing B1 is fitted to the rotating shaft 20 with a clearance fit that is close to an intermediate fit. In this embodiment, the outer circumference of the first bearing B1 is the outer ring 31. That is, in this embodiment, the outer ring 31 of the first bearing B1 is clearance-fitted to the input side insertion passage portion R41. More specifically, in this embodiment, the outer circumference of the outer ring 31 is clearance-fitted to the inner circumference F41 of the input side insertion passage portion of the insertion passage inner circumference F4 of the carrier 4.

[0046] In this embodiment, the inner circumference portion (inner ring 32) of the first bearing B1 is firmly fixed mainly to the rotating shaft 20 of the sun gear 2. On the other hand, the outer circumference portion (outer ring 31) of the first bearing B1 is fixed to the carrier 4 with less force than when the inner circumference portion (inner ring 32) of the first bearing B1 is fixed to the rotating shaft 20. Therefore, when attempting to pull out the sun gear unit U from inside the carrier 4, the sun gear unit U can be easily pulled out from the carrier 4.

[0047] The C-ring 9 is fitted into a fitting groove 4g formed on the input side of either the inner circumferential surface F4 of the insertion passage of the carrier 4 or the outer circumferential surface F2 of the rotating shaft 20, near the input side end 20e of the rotating shaft 20, thereby preventing the first bearing B1 from coming out from the input side. In this embodiment, the rotating shaft 20 has a connection hole 2h for connecting, for example, the drive shaft of a motor. In this embodiment, the connection hole 2h penetrates the rotating shaft 20 in the axial direction.

[0048] In this embodiment, the fitting groove 4g is formed on the inner circumferential surface of the input side end (cylinder wall 4d) of the carrier 4. More specifically, the fitting groove 4g is located on the inner circumferential surface F41 of the input side insertion passage portion of the inner circumferential surface F4 of the insertion passage inner circumferential surface F41 of the carrier 4, and is further formed on the input side of the inner circumferential surface F41 of the input side insertion passage portion. In this embodiment, the fitting groove 4g is an annular fitting groove, and the fitting groove 4g extends annularly around the entire circumference in the circumferential direction around the axis O. A C-ring 9 can be removably snap-fitted into the fitting groove 4g. A portion of the C-ring 9 fitted into the fitting groove 4g protrudes radially inward from the inner circumferential surface F41 of the input side insertion passage portion. The protruding portion of the C-ring 9 can be brought into contact with the input side end of the outer circumference portion of the first bearing B1. In this embodiment, the protruding portion of the C-ring 9 is in contact with the input side end of the outer ring 31 of the first bearing B1. Therefore, in this embodiment, the first bearing B1 is held in place in the axial direction by a C-ring 9 fitted into the fitting groove 4g of the carrier 4, so as not to come out from the input side end 20e of the rotating shaft 20.

[0049] On the other hand, in this embodiment, the rotating shaft 20 has a stepped surface F23 on the output side of the outer circumferential surface F2 of the rotating shaft 20 that positions the first bearing B1 toward the output side. The stepped surface F23 is oriented toward the input side. Therefore, the stepped surface F23 positions the first bearing B1 toward the output side by contacting the inner circumferential portion of the first bearing B1 in the axial direction. In this embodiment, the stepped surface F23 positions the first bearing B1 toward the output side by contacting the inner ring 32 of the first bearing B1 in the axial direction. As a result, the first bearing B1 is positioned in the axial direction by the stepped surface F23 of the rotating shaft 20 and the C-ring 9, and its axial movement relative to the rotating shaft 20 is restricted.

[0050] Furthermore, in this embodiment, the inner circumferential surface F4 of the insertion passage of the carrier 4 is provided with a stepped surface F43 on the output side for positioning the first bearing B1. The stepped surface F43 is oriented toward the input side. Therefore, the stepped surface F43 contacts the outer circumferential portion of the first bearing B1 in the axial direction, thereby positioning the first bearing B1 toward the output side. In this embodiment, the stepped surface F43 contacts the outer ring 31 of the first bearing B1 in the axial direction, thereby positioning the first bearing B1 toward the output side. As a result, the first bearing B1 is positioned axially by the stepped surface F43 of the carrier 4 and the C-ring 9, and its axial movement relative to the carrier 4 is restricted.

[0051] In the planetary gear mechanism M1, the rotation axis 20 of the sun gear 2 is positioned radially by the first bearing B1, thereby suppressing displacement of the rotation axis 20 with respect to the axis O. In addition, in the planetary gear mechanism M1, the rotation axis 20 and the carrier 4 are positioned axially via the first bearing B1, which is restricted in the axial direction by stepped surfaces (F23, F43) and a C-ring 9, thereby restricting the axial movement of the rotation axis 20 relative to the carrier 4. Therefore, in the planetary gear mechanism M1, and by extension the planetary gear device A1, the sun gear 2 connected to the rotation axis 20 has its potential displacement with respect to the axis O suppressed and its axial movement restricted within the carrier 4.

[0052] On the other hand, as shown in Figure 4, the planetary gear mechanism M1 further comprises an internal fixed gear element 7 having an internal gear 7b that meshes with the compound planetary gear 3, and a second bearing B2. The second bearing B2 rotatably supports the internal fixed gear element 7 and the carrier 4. In this embodiment, the second bearing B2 is a rolling bearing, similar to the first bearing B1. However, the second bearing B2 can also be of the same type as the first bearing B1.

[0053] In this embodiment, the internal gear fixed gear element 7 comprises a housing 7a and an internal gear 7b fixed inside the housing 7a. In this embodiment, the central axes of the housing 7a and the internal gear 7b are the same as axis O. That is, in this embodiment, the central axis of the internal gear fixed gear element 7 is the same as axis O. In this embodiment, the housing 7a is fixed to a fixed object such as a case. As a result, the internal gear fixed gear element 7 is a fixed element that cannot rotate around axis O.

[0054] Furthermore, in this embodiment, the internal gear fixed gear element 7 is provided with a through passage R7 at the input end 7a1 of the internal gear fixed gear element 7, which penetrates the input end 7a1 in the axial direction and is located on the input end (cylinder wall 4d) of the carrier 4.

[0055] In this embodiment, the input end 7a1 of the internal fixed gear element 7 is the input end of the housing 7a. In this embodiment, the input end of the housing is a partition wall having a circular outer shape when viewed in the axial direction, as shown in Figure 2. As shown in Figure 4, the input pin support portion 4a of the carrier 4 and the internal gear 7b are arranged at the input end 7a1 of the internal fixed gear element 7 with the internal teeth 7c of the internal gear 7b meshing with the external teeth 3c1 of the input planetary gear 3a.

[0056] In this embodiment, the central axis of the through passage R7 is coaxial with axis O. That is, in this embodiment, the through passage R7 is located on the same axis as the central axis of the internal gear fixed element 7. In this embodiment, the cylindrical wall 4d of the carrier 4 is located in the through passage R7. In this embodiment, the second bearing B2 is exposed from the internal gear fixed element 7 through the input side opening of the through passage R7.

[0057] The second bearing B2 rotatably supports the input end (cylinder wall 4d) of the carrier 4 and the input end 7a1 of the internal gear fixed element 7 within the through passage R7. In this embodiment, the second bearing B2 rotatably supports the cylinder wall 4d of the carrier 4 and the input end 7a1 of the internal gear fixed element 7 in the radial direction. As a result, the carrier 4 can rotate around the axis O with respect to the internal gear fixed element 7.

[0058] In this embodiment, the second bearing B2 is press-fitted into the outer circumferential surface F45 of the cylindrical wall 4d of the carrier 4 and the inner circumferential surface F7 of the through passage R7 of the internal fixed gear element 7 (housing 7a), which forms the through passage R7 at the input end 7a1 of the internal fixed gear element 7, thereby rotatably supporting the carrier 4 with respect to the internal fixed gear element 7.

[0059] Furthermore, in this embodiment, the second bearing B2 is positioned on the output side by the inner circumference of the second bearing B2 contacting the input-side pin support portion 4a of the carrier 4 in the axial direction. In this embodiment, the input-side pin support portion 4a of the carrier 4 is located on the output side of the second bearing B2. In this embodiment, the second bearing B2 is positioned on the output side by the inner ring 32 of the second bearing B2 contacting the input-side pin support portion 4a from the input side.

[0060] In this embodiment, the composite planetary gear 3 comprises an input-side planetary gear (first planetary gear) 3a that meshes with the sun gear 2, and an output-side planetary gear (second planetary gear) 3b that is integrally provided with the input-side planetary gear 3a. In this embodiment, the output-side planetary gear 3b meshes with the internal gear element 6.

[0061] The internal gear element 6 comprises a partition wall 6a, a circumferential wall 6b projecting axially from the partition wall 6a, and internal teeth 6c formed radially inward of the circumferential wall 6b. In this embodiment, the central axes of the partition wall 6a and the circumferential wall 6b are the same as axis O. That is, in this embodiment, the central axis of the internal gear element 6 is the same as axis O. In this embodiment, the partition wall 6a is a partition wall that closes the output side opening end of the circumferential wall 6b. The circumferential wall 6b extends annularly around the entire circumference in the circumferential direction around axis O, and also extends from the partition wall 6a toward the input side. The internal teeth 6c of the internal gear element 6 mesh with the external teeth 3c2 of the output side planetary gear 3b of the composite planetary gear 3.

[0062] The compound planetary gear 3 is rotatably supported by carrier pins 5 provided on the carrier 4. In this embodiment, the central axis of the carrier 4 is also the same as axis O. The carrier pins 5 are arranged at circumferential intervals around axis O. As a result, the compound planetary gear 3 can revolve around axis O together with the carrier pins 5, while rotating on its own axis around the carrier pins 5, in synchronization with the rotation of the carrier 4 around axis O. In this embodiment, the planetary gear mechanism M1 includes four compound planetary gears 3 along with the carrier pins 5. However, the number of compound planetary gears 3 (carrier pins 5) can be two or more.

[0063] In this embodiment, the output planetary gear 3b is integrally provided by spline fitting inside the input planetary gear 3a. As a result, the input planetary gear 3a and the output planetary gear 3b can rotate integrally around the carrier pin 5 as a composite planetary gear 3. In this embodiment, the output planetary gear 3b is a different planetary gear from the input planetary gear 3a. In this embodiment, the output planetary gear 3b has fewer teeth and a smaller diameter than the input planetary gear 3a. As a result, in this embodiment, the composite planetary gear 3 can function with the output planetary gear 3b as a reduction gear by using the input planetary gear 3a as the input gear.

[0064] In this embodiment, the input planetary gear 3a is an external gear equipped with external teeth 3c1. The input planetary gear 3a can revolve around the sun gear 2 on axis O while rotating on the carrier pin 5, with the external teeth 3c1 of the input planetary gear 3a meshing with the external teeth 2a of the sun gear 2 and the internal teeth 7c of the internal gear 7b of the internal fixed gear element 7. On the other hand, in this embodiment, the output planetary gear 3b is an external gear equipped with external teeth 3c2. The output planetary gear 3b can revolve around the sun gear 2 on axis O while rotating on the carrier pin 5, with the external teeth 3c2 of the output planetary gear 3b meshing with the internal teeth 6c of the circumferential wall 6b of the internal rotating gear element 6.

[0065] Furthermore, in this embodiment, the planetary gear mechanism M1 further includes a third bearing B3 that rotatably supports the internal rotating gear element 6 relative to the internal fixed gear element 7. This allows the internal rotating gear element 6 to rotate around the axis O relative to the internal fixed gear element 7. In this embodiment, the third bearing B3 is a rolling bearing, similar to the first bearing B1. However, the third bearing B3 can also be of the same type as the first bearing B1.

[0066] In this embodiment, the third bearing B3 is press-fitted between the outer circumferential surface F64 of the circumferential wall 6b of the internal gear element 6 and the inner circumferential surface F72 of the internal fixed gear element 7 (housing 7a). As a result, the third bearing B3 rotatably supports the internal gear element 6 relative to the internal fixed gear element 7 in the radial direction.

[0067] In this embodiment, the input end of the third bearing B3 is supported by the stepped surface F73 of the internal gear fixed element 7 (housing 7a). In this embodiment, the third bearing B3 is housed between the housing 7a and the cover 10, which is attached to the housing 7a of the internal gear fixed element 7. In this embodiment, the cover 10 is an annular cover that extends in an annular manner around the entire circumference of the axis O. In this embodiment, the input end of the cover 10 has a stepped surface F10 formed radially inward. In this embodiment, the output end of the third bearing B3 abuts against the stepped surface F65 of the internal gear rotating element 6 (partition wall 6a) and the stepped surface F10 of the cover 10.

[0068] In addition, a fourth bearing B4 is positioned between the internal gear element 6 and the carrier 4, rotatably supporting the internal gear element 6 and the carrier 4 in the radial direction. In this embodiment, the fourth bearing B4 is a rolling bearing, similar to the first bearing B1. However, the fourth bearing B4 can also be of the same type as the first bearing B1.

[0069] In this embodiment, the internal gear element 6 has a carrier housing recess n1 in the partition wall 6a that accommodates the output-side pin support portion 4b of the two pin support portions of the carrier 4. In addition, the output-side pin support portion 4b of the carrier 4 is positioned in the carrier housing recess n1.

[0070] Furthermore, in this embodiment, the internal gear element 6 is provided with an internal gear element side protrusion 6d in the carrier housing recess n1. The internal gear element side protrusion 6d protrudes toward the input side from the input side surface F632) of the carrier housing recess n1 formed in the partition wall 6a. The internal gear element side protrusion 6d forms the carrier housing recess n1 into an annular carrier housing recess n1. On the other hand, in this embodiment, the carrier 4 is provided with an internal gear element housing recess n2 in the output side pin support portion 4b. The internal gear element side protrusion 6d is housed in the internal gear element housing recess n2.

[0071] In this embodiment, the fourth bearing B4 is positioned between the internal gear element side protrusion 6d of the internal gear element 6 and the internal gear element housing recess n2 of the carrier 4. As a result, the fourth bearing B4 rotatably supports the internal gear element 6 and the carrier 4 in the radial direction.

[0072] The fourth bearing B4 is press-fitted into the outer circumferential surface F62 that forms the convex portion 6d on the internal gear element side of the internal gear element 6 and the inner circumferential surface F46 that forms the recess n2 that accommodates the internal gear element of the carrier 4, thereby rotatably supporting the carrier 4 and the internal gear element 6 in the radial direction. As a result, the carrier 4 and the internal gear element 6 can rotate relative to each other in the circumferential direction around the axis O.

[0073] According to the planetary gear mechanism M1, and by extension the planetary gear device 1A, the rotation input to the sun gear 2 is extracted as reduced rotation from the internal rotating gear element 6 by the compound planetary gear 3, together with the carrier 4, rotating radially inward of the internal fixed gear element 7.

[0074] In a planetary gear mechanism, the sun gear rotates at the same rotational speed as the driving element (e.g., motor) or the driven element (e.g., robot hand), and because it meshes with multiple planetary gears, it experiences significantly more wear than other components. For this reason, it is preferable that the sun gear can be replaced independently. Furthermore, if the sun gear is supported via a bearing, and the sun gear is supported with a misalignment relative to the axis O, there is a concern that this could lead to tilting of the sun gear, thereby reducing the output efficiency of the planetary gear mechanism.

[0075] On the other hand, as described in Patent Document 1, there is a known technique for centering the sun gear by using an intermediate member that connects the sun gear and the drive-side elements (driven-side elements) of a planetary gear mechanism, thereby preventing wear and positioning of the sun gear. However, the invention described in Patent Document 1 primarily involves replacing the entire planetary gear mechanism when the sun gear is worn, and does not envision replacing only the sun gear. Therefore, there is room for improvement in terms of reducing maintenance costs. Furthermore, in the invention described in Patent Document 1, the assembly accuracy of the sun gear and its bearings depends on the mounting accuracy of the drive-side elements (driven-side elements) and the intermediate member. Therefore, there is still concern that the sun gear may be misaligned with respect to the axis O in the invention described in Patent Document 1.

[0076] Furthermore, some planetary gear mechanisms have multiple bearings arranged along the axial direction between the rotating shaft of the sun gear and the carrier, and collars are fitted into the gaps between these bearings to restrict the axial movement of these bearings (for example, Technical paper "Development of a small, high-reduction bilateral gear for moving objects," Mitsubishi Heavy Industries Technical Report Vol. 59 No. 1 (2022), New Products and New Technologies Special Feature). This planetary gear system aligns the sun gear with respect to its axis O by providing multiple bearings that support the rotating shaft of the sun gear.

[0077] However, the planetary gear mechanism described above has multiple fitting parts (multiple bearings and positioning collars for positioning these bearings) that must be fixed axially between the rotating shaft of the sun gear and the carrier for positioning purposes. In other words, a planetary gear device employing such a configuration requires multiple bearings on the rotating shaft of the sun gear, and further requires positioning collars on the rotating shaft of the sun gear to position these multiple bearings axially. For this reason, the invention described in the non-patent literature is also a concern because the tolerances for concentricity and coaxiality of the multiple fitting parts (bearings, positioning collars) with respect to the rotating shaft accumulate, which may cause the sun gear to be misaligned with respect to axis O. Furthermore, assembling the fitting parts complicates the production process and increases product costs, and the cumulative arrangement of parts in the axial direction leads to an increase in shaft length. This increase in shaft length is particularly disadvantageous for composite planetary gear mechanisms characterized by their thin and flat structure.

[0078] In contrast, with the planetary gear mechanism M1, as explained below, it is possible to choose to replace only two components: the sun gear 2 and the first bearing B1.

[0079] Figure 6 shows the planetary gear system 1A in an oblique view from the input side.

[0080] When removing the sun gear 2 and the first bearing B1 from the planetary gear unit 1A, the C-ring 9 is first removed from the carrier 4. The C-ring 9 can be removed through the input side opening A41 of the insertion passage R4, for example, by using a tool (e.g., pliers). Figure 7 shows an illustrative example of the C-ring 9 removed from the planetary gear unit 1A. Figure 8 shows a perspective view of the planetary gear unit 1A from Figure 6 with the C-ring 9 from Figure 7 removed.

[0081] After removing the C-ring 9, the sun gear 2 is pulled out together with the first bearing B1 through the input-side opening A41 formed at the input-side end 4e1 of the carrier 4. In this embodiment, the outer ring 31 of the first bearing B1 is clearance-fitted to the inner circumferential surface F41 of the input-side insertion passage portion of the inner circumferential surface F4 of the insertion passage of the carrier 4. Therefore, the first bearing B1 can be easily pulled out to the input side through the input-side opening A41. On the other hand, the inner ring 32 of the first bearing B1 is interlock-fitted to the input-side outer circumferential surface F21 of the outer circumferential surface F2 of the rotating shaft 20. As a result, the first bearing B1 can be pulled out to the input side as a sun gear unit U to which the sun gear 2 is fixed.

[0082] In addition, as shown in Figure 5, in this embodiment, the first bearing B1 has an outer diameter D3 that is larger than the tip circle diameter D2 of the sun gear 2, and furthermore, the inner diameter D42 of the output side insertion passage portion R42 of the insertion passage R4 formed in the carrier 4 is larger than the tip circle diameter D2 of the sun gear 2. Therefore, according to this embodiment, the first bearing B1 can be easily pulled out to the input side through the input side opening A41 as a sun gear unit U to which the sun gear 2 is fixed. In this embodiment, the first bearing B1, and by extension the sun gear unit U, can also be removed through the input side opening A41 of the insertion passage R4 by, for example, using a tool (for example, pliers) to grasp the rotating shaft 20 and pull it out.

[0083] Figure 9 shows a perspective view of the planetary gear assembly 1A from Figure 8 with the sun gear unit U removed. Furthermore, Figure 10 shows a perspective view of the sun gear unit U removed from the planetary gear assembly 1A from Figure 8. Thus, with the planetary gear assembly 1A, only the sun gear 2 and the first bearing B1 can be replaced without disassembling or replacing the entire planetary gear assembly 1A.

[0084] Furthermore, in this embodiment, the sun gear unit U can be separated into a sun gear 2 equipped with a rotating shaft 20 and a first bearing B1. In this embodiment, the inner ring 32 of the first bearing B1 is interlocked with the input-side outer circumferential surface F21 of the outer circumferential surface F2 of the rotating shaft 20, so the first bearing B1 can be removed from the rotating shaft 20 of the sun gear 2. In this embodiment, the first bearing B1 attached to the sun gear 2 can also be removed, for example, by using a tool (for example, pliers).

[0085] Figure 11 shows a perspective view of the first bearing B1 removed from the sun gear unit U in Figure 10. Figure 12 also shows a perspective view of the sun gear 2, with the first bearing B1 removed from the sun gear unit U in Figure 10, together with the rotating shaft 20. Thus, with the planetary gear system 1A, it is possible to replace only the sun gear 2 or only the first bearing B1 without disassembling or replacing the entire planetary gear system 1A. In other words, with the planetary gear system 1A, and by extension the planetary gear mechanism M1, at least the sun gear 2 and the first bearing B1 can be replaced by removing the C-ring 9 from the carrier 4 and then pulling out the first bearing B1.

[0086] As shown in Figure 5, the insertion passage R4 formed in the carrier 4 has an inner diameter D42 large enough to allow the sun gear 2 to pass through, and the first bearing B1 is fitted into the insertion passage R4. Furthermore, as shown in Figure 6, the input side opening A41 of the insertion passage R4 is exposed through the input side opening A7 of the through passage R7 of the internal tooth fixed gear element 7. In other words, the planetary gear unit 1A, and by extension the planetary gear mechanism M1, has a structure that allows the sun gear 2 and the first bearing B1 to be replaced without having to remove the internal tooth fixed gear element 7 (housing 7a).

[0087] Furthermore, as shown in Figure 5, the sun gear 2 is supported on the carrier 4 only by the first bearing B1 attached to the rotating shaft 20. In other words, the planetary gear unit 1A, and by extension the planetary gear mechanism M1, limits the positioning (mounting) of the sun gear 2 and the first bearing B1 to the carrier 4.

[0088] Furthermore, the components accumulated on the rotating shaft 20 are substantially limited to two parts: a first bearing B1 that supports the carrier 4 and the rotating shaft 20 within the insertion passage R4 formed in the carrier 4, and a C-ring 9 that positions the first bearing B1. In this case, by making the tip circle diameter D2 of the sun gear 2 smaller than the outer diameter D3 of the first bearing B1, the sun gear 2 together with the first bearing B1 can be moved in and out of the insertion passage R4 formed in the carrier 4.

[0089] With the planetary gear system 1A, when the sun gear 2 and the first bearing B1 wear out, in addition to replacing the entire planetary gear system 1A and, by extension, the planetary gear mechanism M1, it is possible to offer the option of replacing only the sun gear unit U. Furthermore, with the planetary gear system 1A and, by extension, the planetary gear mechanism M1, the replacement process consists of only two steps: attaching and detaching the sun gear unit U by removing and attaching the C-ring 9, and attaching and detaching the sun gear 2 to the first bearing B1. As a result, the replacement work can be completed using only general-purpose tools (e.g., pliers), which reduces the cost and man-hours required for functional restoration.

[0090] Furthermore, with the planetary gear system 1A, the sun gear 2 does not interfere with any parts other than the composite planetary gear 3. The first bearing B1 also does not interfere with any parts other than the rotating shaft 20 and the carrier 4. Moreover, since the sun gear 2 is supported by the carrier 4 only by the first bearing B1, interference with surrounding parts is minimized, and positional deviation with respect to the axis O is also minimized. In addition, a positioning structure for the sun gear 2 that does not depend on the mounting accuracy of the intermediate parts (connecting parts) that connect the power source and the planetary gear system 1A can be adopted. For this reason, with the planetary gear system 1A, alignment between each part attached to the rotating shaft 20 and the rotating shaft 20 is unnecessary, thus reducing the assembly man-hours for the planetary gear system 1A and, consequently, the planetary gear mechanism M1.

[0091] As described above, with the planetary gear system 1A, in addition to replacing the entire planetary gear system 1A, it is possible to choose to replace only two components, the sun gear 2 and the first bearing B1. Furthermore, it is possible to provide a planetary gear mechanism M1 and a planetary gear system 1A equipped with the planetary gear mechanism M1, in which the assembly of the two components, the sun gear 2 and the first bearing B1, is simplified.

[0092] Furthermore, with the planetary gear system 1A, the axial positioning (mounting and movement restriction) of the sun gear 2 and the first bearing B1 within the planetary gear system 1A can be determined by a single component, the C-ring 9. Therefore, with the planetary gear system 1A, the number of parts in the planetary gear system 1A, and consequently the planetary gear mechanism M1, can be reduced, while also reducing assembly man-hours and product costs. In addition, because the first bearing B1 is positioned by the C-ring 9, the number of parts accumulated on the rotating shaft 20 is minimized, thereby significantly shortening the axial length of the planetary gear system 1A, and consequently the planetary gear mechanism M1.

[0093] Furthermore, with the planetary gear unit 1A, since only the sun gear unit U can be attached to and detached from the planetary gear unit 1A, the sun gear 2 can be replaced with a sun gear suited to the application. For example, by replacing the sun gear 2 with a sun gear with increased tooth thickness, the backlash and angular transmission error can be adjusted to arbitrary or desired values. In addition, the strength of the external teeth 2a of the sun gear 2 can be improved by changing the shape, material, etc. of the external teeth 2a. In this case, it becomes possible to extend the lifespan of the planetary gear unit 1A, and consequently the planetary gear mechanism M1, reduce noise, and lower costs.

[0094] Furthermore, in this embodiment, the rotating shaft 20 is supported by the carrier 4 in the radial direction via the first bearing B1, while the first bearing B1 is positioned in the axial direction between the C-ring 9, the stepped surface F23 of the rotating shaft 20, and the stepped surface F43 of the carrier 4. As a result, the sun gear 2 is prevented from misaligning with respect to the axis O within the carrier 4, and its movement in the axial direction is restricted. In this case, wear of the sun gear 2 and the first bearing B1 is suppressed, and transmission efficiency can be improved.

[0095] Furthermore, when the first bearing B1 is restricted by the stepped surface F23 of the rotating shaft 20 and the stepped surface F43 of the carrier 4, the first bearing B1 is positioned between the input-side insertion passage portion R41 of the insertion passage R4 of the carrier 4 and the input-side rotating shaft portion 21 of the rotating shaft 20. In this case, by suppressing the increase in the radial dimension of the carrier 4, it is possible to reduce the diameter of the planetary gear mechanism M1 and, consequently, the planetary gear device A1.

[0096] Furthermore, in this embodiment, the input end (cylinder wall 4d) of the carrier 4 is supported by the input end 7a1 of the internal gear fixed element 7 (housing 7a) via the second bearing B2, allowing the sun gear unit U to be exposed to the outside through the insertion passage R4 of the carrier 4. This makes it possible to easily insert and remove the sun gear unit U into and out of the carrier 4 without removing the housing 7a from the internal gear fixed element 7.

[0097] Furthermore, according to this embodiment, the input end (cylinder wall 4d) of the carrier 4 is supported by the input end 7a1 of the internal gear fixed element 7 (housing 7a) via the second bearing B2, eliminating the need for a bearing to support the rotating shaft 20 and the internal gear fixed element 7 (housing 7a). As a result, the shaft length of the planetary gear device A1, and consequently the planetary gear mechanism M1, can be reduced, thereby decreasing the number of parts and assembly man-hours.

[0098] Furthermore, in this embodiment, the planetary gear is a composite planetary gear 3 comprising an input-side planetary gear 3a that meshes with the sun gear 2, and an output-side planetary gear 3b that is integrally provided with the input-side planetary gear 3a. In this case, the planetary gear device A1, and by extension the planetary gear mechanism M1, can have a thin and flat structure.

[0099] Furthermore, the planetary gear mechanism M1 includes an internal rotating gear element 6 that meshes with the output planetary gear 3b, a third bearing B3 that rotatably supports the internal fixed gear element 7 and the internal rotating gear element 6, and a fourth bearing B4 that rotatably supports the carrier 4 and the internal rotating gear element 6. In this case, the carrier 4 is firmly positioned inside the planetary gear mechanism M1 by the internal fixed gear element 7 and the internal rotating gear element 6. Therefore, in this case, wear of the sun gear 2 and the first bearing B1 is further suppressed in the planetary gear mechanism M1, and consequently in the planetary gear device 1A, and the transmission efficiency can be further improved.

[0100] The above describes only exemplary embodiments of the present invention, and various modifications are possible according to the claims. In this embodiment, the planetary gear mechanism M1 is a planetary gear mechanism device using a compound planetary gear 3 consisting of two-stage gears, but a planetary gear mechanism using planetary gears consisting of single gears may be used instead of the compound planetary gear 3. Furthermore, in a planetary gear device equipped with the planetary gear mechanism according to this embodiment, the internal tooth rotating gear element 6 can be used as the input rotating element, while the sun gear 2 can be used as the output rotating element. Also, the planetary gear mechanism M1 may consist of a sun gear 2 with a rotating shaft 20, a carrier 4 equipped with planetary gears, a first bearing B1, and a C-ring 9. [Explanation of symbols]

[0101] 1A: Planetary gear set, 2a: External teeth, O: Axis (central axis of the planetary gear set), 2: Sun gear, 2h: Connection hole, 3: Compound planetary gear, 3a: Input side planetary gear (first planetary gear), 3b: Output side planetary gear (second planetary gear), 3c1: External teeth, 4: Carrier, 4a: Input side pin support portion, 4b: Output side pin support portion, 4b1: Large diameter portion of output side pin support portion, 4b2: Small diameter portion of output side pin support portion, 4c: Connecting wall, 4d: Cylinder wall (end on one side in the axial direction), 4e2: Output side end of input side pin support portion, 4e1: Input side end of carrier, 4e2: Output side end of input side pin support portion, 4e3: Input side end of output side pin support portion, 4g: Fitting groove, 5: Carrier pin, 5a: Input side end, 5b: Output end, 6: Internal gear element (second internal gear element), 6a: Partition wall, 6b;Circumferential wall, 6c: internal teeth, 6d: protrusion on the internal tooth rotating gear element side, 7: internal tooth fixed gear element (internal tooth gear element), 7a: housing, 7a1: input side end of internal tooth fixed gear element, 7b: internal tooth gear, 7c: internal teeth, 9: C-ring, 10: cover, 20: rotating shaft, 21: input side rotating shaft portion, 22: output side rotating shaft portion, 31: outer ring, 32: inner ring, 33: rolling element, A4: opening hole, A41: input side opening, A42: output side opening, A7: input side opening of through passage, B1: first bearing (bearing), B2: second bearing, B3: third bearing, B4: fourth bearing, D2: tip circle diameter of sun gear, D3: outer diameter of first bearing, D21: outer diameter of input side rotating shaft portion, D22: outer diameter of output side rotating shaft portion, D41: Inner diameter of the input side insertion passage (diameter of the input side opening), D42: Inner diameter of the output side insertion passage (diameter of the output side opening), F2: Outer surface of the rotating shaft, F21: Outer surface of the input side, F22: Outer surface of the output side, F23: Stepped surface, F4: Inner surface of the carrier insertion passage (inner surface of the carrier), F41: Inner surface of the input side insertion passage, F42: Inner surface of the output side insertion passage, F43: Stepped surface, F44: Radial inner surface of the connecting wall, F45: Outer surface of the cylindrical wall of the carrier, F46: Inner surface of the recess housing the internal gear element, F62: Outer surface of the protrusion on the internal gear element side, F632: Input side surface of the carrier housing recess, F64: Outer surface of the peripheral wall, F65: Stepped surface of the internal gear element (partition wall), F7: Inner surface of the through passage, F72: Inner surface of the internal fixed gear element (housing), F73: Stepped surface of internal fixed gear element (housing), F10: Stepped surface of cover, M1: Planetary gear mechanism, n1: Carrier housing recess, n2: Internal rotating gear element housing recess, R4: Insertion passage, R41: Input side insertion passage portion, R42: Output side insertion passage portion, R7: Through passage, S4: Housing space, U: Planetary gear unit;

Claims

1. It comprises a sun gear with a rotating shaft, a carrier with planetary gears, a bearing that rotatably supports the rotating shaft and the carrier, and a C-ring that can be attached to or detached from the rotating shaft or the carrier. The carrier comprises an insertion passage into which the sun gear and the rotating shaft connected to the sun gear can be inserted axially together with the bearing, and a housing space connected to the insertion passage and capable of housing the sun gear. The bearing has an outer diameter larger than the tip circle diameter of the sun gear and is fitted tightly to the outer circumferential surface of the rotating shaft, while being fitted loosely to the inner circumferential surface of the carrier that forms the insertion passage for the carrier. The C-ring fits into a fitting groove formed on one side in the axial direction near the input / output end of the rotating shaft, either on the inner circumferential surface of the carrier or the outer circumferential surface of the rotating shaft, thereby preventing the bearing from coming off from that side in the axial direction.

2. The rotating shaft has a stepped surface on the outer circumferential surface of the rotating shaft, on the side in the axial direction closest to the sun gear, which positions the bearing on the other side in the axial direction. The planetary gear mechanism according to claim 1, wherein the carrier has a stepped surface on the other side in the axial direction of the inner circumferential surface of the carrier for positioning the bearing.

3. The system further comprises an internal gear element having an internal gear that meshes with the planetary gear, and a second bearing that rotatably supports the internal gear element and the carrier. The internal gear element is provided with a through passage at one end of the internal gear element in the axial direction, which penetrates the one end of the internal gear element in the axial direction in the axial direction and is where the one end of the carrier in the axial direction is positioned. The planetary gear mechanism according to claim 1, wherein the second bearing rotatably supports one axial end of the carrier and one axial end of the internal gear element within the through passage.

4. The planetary gear mechanism according to claim 1, wherein the planetary gear is a composite planetary gear comprising a first planetary gear that meshes with the sun gear and a second planetary gear provided integrally with the first planetary gear.

5. A second internal gear element that meshes with the second planetary gear, A third bearing rotatably supports the aforementioned internal gear element and the second internal gear element, The planetary gear mechanism according to claim 4, further comprising a fourth bearing that rotatably supports the carrier and the second internal gear element.

6. A planetary gear device comprising a planetary gear mechanism as described in any one of claims 1 to 5.

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