Planetary gear system

Abstract

To provide a planetary gear device capable of suppressing an occurrence of abrasion of a planetary carrier due to centrifugal force applied to a planetary gear.SOLUTION: A planetary gear device 1 includes: a plurality of planetary gears 2 in which helical gears 210 and 220 are formed on each outer periphery of a large diameter part 21 and a small diameter part 22; a planetary carrier 3 provided with a plurality of storage holes 30 for storing each of the plurality of planetary gears 2; a sun gear 4 having external teeth 41 meshing with the helical gear 210 formed in the large diameter part 21 of the plurality of planetary gears 2; and an internal gear 5 having internal teeth 511 meshing with the helical gear 220 formed in the small diameter part 22. The storage holes 30 include a large diameter arc hole 301 for storing the large diameter part 21 and a small diameter arc hole 302 for storing the small diameter part 22. The planetary carrier 3 includes a small diameter part outer periphery support part 33 for supporting a part in an axial direction of the small diameter part 22 from an outer peripheral side in a radial direction perpendicular to a rotation axis O1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a planetary gear system. [Background technology]

[0002] Conventionally, planetary gear systems have been used as differential devices to distribute the driving force of a vehicle's power source to a pair of axles (see, for example, Patent Document 1).

[0003] The planetary gear system described in Patent Document 1 comprises a planetary gear having a large-diameter gear section and a small-diameter gear section with different pitch circle diameters, a planetary carrier having a housing support section that supports the planetary gear so that it can rotate, a sun gear having external teeth that mesh with the large-diameter gear section of the planetary gear, and an internal gear having internal teeth that mesh with the small-diameter gear section of the planetary gear. The planetary carrier, sun gear, and internal gear rotate around a common axis of rotation, and the planetary gear rotates while revolving together with the planetary carrier. In order to balance the mechanical strength of the large-diameter gear section and the small-diameter gear section, the small-diameter gear section of the planetary gear is formed to be longer than the large-diameter gear section.

[0004] The planetary carrier's housing support section consists of a first housing hole for housing a large-diameter gear section and a second housing hole for housing a small-diameter gear section. The inner circumferential surface of the first housing hole is formed as a first support surface that slidably supports the tooth tip surface of the large-diameter gear section, and the inner circumferential surface of the second housing hole is formed as a second support surface that slidably supports the tooth tip surface of the small-diameter gear section. The first housing hole opens inward towards the sun gear of the planetary carrier, and the second housing hole opens outward towards the internal gear of the planetary carrier. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2009-281544 [Overview of the project] [Problems that the invention aims to solve]

[0006] In the planetary gear system configured as described above, the first support surface of the first housing hole receives the meshing reaction force with the external teeth of the sun gear in the large-diameter gear portion of the planetary gear, and the second support surface of the second housing hole receives the meshing reaction force with the internal teeth of the internal gear in the small-diameter gear portion of the planetary gear, so that the rotation axis of the planetary gear becomes parallel to the rotation axis of the planetary carrier. However, for example, during high-speed steady-state driving with low torque, such as when a vehicle is traveling at a constant speed on a highway, the centrifugal force generated by the revolution of the planetary gear causes a pressing force acting on the small-diameter gear portion of the planetary gear toward the internal gear, which is greater than the reaction force due to the meshing between the small-diameter gear portion of the planetary gear and the internal teeth of the internal gear, and the small-diameter gear portion of the planetary gear may come into contact with the edge at the opening end of the second housing hole. Furthermore, if the planetary gear continues to rotate in this contact state for an extended period, wear on the edge of the second housing hole will be accelerated, potentially leading to increased play in the planetary gear relative to the planetary carrier.

[0007] Therefore, the present invention aims to provide a planetary gear system that can suppress the occurrence of wear on the planetary carrier caused by centrifugal force acting on the planetary gear. [Means for solving the problem]

[0008] To achieve the above objective, the present invention provides a plurality of planetary gears, each having helical gears formed on the outer circumference of a large-diameter portion and a small-diameter portion aligned in the axial direction; a planetary carrier having a plurality of housing holes for housing each of the plurality of planetary gears; a sun gear disposed inside the planetary carrier and having external teeth that mesh with the helical gears formed on the large-diameter portions of the plurality of planetary gears; and an internal gear disposed outside the planetary carrier and having internal teeth that mesh with the helical gears formed on the small-diameter portions of the plurality of planetary gears. The present invention provides a planetary gear system comprising a sun gear and an internal gear, wherein the planetary carrier, the sun gear, and the internal gear are rotatable relative to each other about a common axis of rotation, and each of the plurality of housing holes has a large-diameter arc hole having an arc-shaped inner surface on which the cutting edge surface of the helical gear in the large-diameter portion slides, and a small-diameter arc hole having an arc-shaped inner surface on which the cutting edge surface of the helical gear in the small-diameter portion slides, and the planetary carrier has a small-diameter outer peripheral support portion that supports a part of the axial direction of the small-diameter portion from the radial outer peripheral side perpendicular to the axis of rotation. [Effects of the Invention]

[0009] According to the planetary gear system of the present invention, it is possible to suppress the occurrence of wear on the planetary carrier caused by centrifugal force acting on the planetary gear. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view showing a planetary gear system according to an embodiment of the present invention. [Figure 2] This is a perspective view showing multiple planetary gears, planetary carriers, internal gears, a second bearing, and a fourth bearing. [Figure 3] This is a perspective view showing the third bearing, retaining member, closing member, fifth bearing, side washer, sun gear, and center washer. [Figure 4A] This is a cross-sectional view taken along line AA in Figure 1, perpendicular to the axial direction. [Figure 4B]It is a cross-sectional view taken along line B-B of FIG. 1 perpendicular to the axial direction. [Figure 4C] It is a cross-sectional view taken along line C-C of FIG. 1 perpendicular to the axial direction. [Figure 5] It is a perspective cross-sectional view of the planetary carrier. [Figure 6] It is a perspective view of the internal gear. [Figure 7] It is a side view of the planetary gear. [Figure 8] (a) to (c) are cross-sectional views of the planetary gear at lines D-D, E-E, and F-F of FIG. 7. [Figure 9] It is an external perspective view of a part of the planetary gear device. [Figure 10] It is a partial cross-sectional view showing a configuration example of a planetary gear device having a planetary carrier according to a comparative example. [Figure 11] It is an external perspective view of a part of the planetary gear device according to a comparative example. [Embodiments for Carrying Out the Invention]

[0011] [Embodiment] Embodiments of the present invention will be described with reference to FIGS. 1 to 9. Note that the embodiments described below are shown as preferred specific examples for carrying out the present invention, and although there are parts that specifically illustrate various technically preferable technical matters, the technical scope of the present invention is not limited to this specific aspect.

[0012] FIG. 1 is a cross-sectional view showing a planetary gear device 1 according to an embodiment of the present invention. The planetary gear device 1 mainly includes a plurality of planetary gears 2, a planetary carrier 3, a sun gear 4, an internal gear 5, and a closing member 6 that closes the opening of the internal gear 5. The sun gear 4 is disposed inside the planetary carrier 3, and the internal gear 5 is disposed outside the planetary carrier 3. The planetary carrier 3, the sun gear 4, and the internal gear 5 are relatively rotatable about a common rotation axis O1. Hereinafter, the direction parallel to the rotation axis O1 is referred to as the axial direction.

[0013] The planetary carrier 3 is connected to the first shaft 71 in a manner that prevents relative rotation. The sun gear 4 is connected to the second shaft 72 in a manner that prevents relative rotation. The internal gear 5 is connected to the third shaft 73 in a manner that prevents relative rotation. In Figure 1, the first to third shafts 71 to 73 are shown by dashed lines (two-dot lines). The second shaft 72 is cylindrical with the first shaft 71 inserted through its center.

[0014] When the planetary gear system 1 is used as a differential gear for a vehicle, for example, the driving force of a drive source input to the planetary gear system 1 from the first shaft 71, which is an input shaft, is distributed and output to the second shaft 72 and the third shaft 73, which are a pair of output shafts. The second shaft 72 is, for example, a front-wheel propeller shaft that transmits driving force to the front wheels of a four-wheel drive vehicle. The third shaft 73 is, for example, a rear-wheel propeller shaft that transmits driving force to the rear wheels of a four-wheel drive vehicle.

[0015] Furthermore, the planetary gear unit 1 includes a first bearing 11 fitted externally to the internal gear 5, a second bearing 12 fitted internally to the internal gear 5 and supporting the first shaft 71, a third bearing 13 fitted internally to the closing member 6 and supporting the second shaft 72, a fourth bearing 14 positioned between the internal gear 5 and the planetary carrier 3, a fifth bearing 15 and side washers 16 positioned between the multiple planetary gears 2 and the closing member 6, a center washer 17 positioned between the planetary carrier 3 and the sun gear 4, and a retaining member 18 that prevents the closing member 6 from coming off. In this embodiment, as an example, the first bearing 11 is a sliding bearing, and the second bearing 12 and the third bearing 13 are needle radial roller bearings. The fourth bearing 14 and the fifth bearing 15 are needle thrust roller bearings. Next, each component of the planetary gear unit 1 will be described in detail with reference to Figures 2 to 9.

[0016] Figure 2 is a perspective view showing multiple planetary gears 2, planetary carriers 3, internal gear 5, second bearing 12, and fourth bearing 14. Figure 3 is a perspective view showing a third bearing 13, retaining member 18, closing member 6, fifth bearing 15, side washer 16, sun gear 4, and center washer 17. Figure 4A is a cross-sectional view taken along line AA of Figure 1, perpendicular to the axial direction. Figure 4B is a cross-sectional view taken along line BB of Figure 1, perpendicular to the axial direction. Figure 4C is a cross-sectional view taken along line CC of Figure 1, perpendicular to the axial direction. Figure 5 is a perspective view of the planetary carrier 3. Figure 6 is a perspective view of the internal gear 5. Figure 7 is a side view of the planetary gear 2. Figures 8(a) to (c) are cross-sectional views of the planetary gear 2 along lines DD, EE, and FF of Figure 7. Figure 9 is an external perspective view of a part of the planetary gear unit 1.

[0017] The sun gear 4 has external teeth 41 formed on its outer circumference, inclined with respect to the axial direction. As shown in Figure 1, a spline fitting portion 42 consisting of a plurality of spline teeth 421 extending in the axial direction is formed on the inner circumference of the sun gear 4. The second shaft 72 is connected to the sun gear 4 in a way that prevents relative rotation by spline fitting into the spline fitting portion 42.

[0018] The internal gear 5 integrally comprises a cylindrical portion 51 that houses the planetary carrier 3 together with a plurality of planetary gears 2, a bottom portion 52 that closes one axial end of the cylindrical portion 51, and a shaft portion 53 that extends axially from the center of the bottom portion 52. Note that the cylindrical portion 51, the bottom portion 52, and the shaft portion 53 may be separate components. Internal teeth 511 are formed on the inner circumference of the cylindrical portion 51, inclined with respect to the axial direction. The opening of the cylindrical portion 51 opposite the bottom portion 52 is closed by a closing member 6. A spline fitting portion 530 consisting of a plurality of spline teeth 531 extending axially is formed on the outer circumference of the shaft portion 53. The third shaft 73 is connected to the internal gear 5 in a manner that prevents relative rotation by spline fitting into the spline fitting portion 530.

[0019] As shown in Figure 7, the planetary gear 2 integrally comprises a large-diameter portion 21 and a small-diameter portion 22 with a smaller outer diameter than the large-diameter portion 21. The planetary gear 2 is held on the planetary carrier 3 so as to be able to rotate around the rotation axis O2. The rotation axis O2 is parallel to the axis of rotation O1. The large-diameter portion 21 and the small-diameter portion 22 are aligned in the axial direction parallel to the rotation axis O2 and the axis of rotation O1. The axial length L2 of the small-diameter portion 22 is longer than the axial length L1 of the large-diameter portion 21, and the center of gravity G of the planetary gear 2 is contained within the small-diameter portion 22. The planetary gear 2 is arranged such that the large-diameter portion 21 faces the closing member 6 side and the small-diameter portion 22 faces the bottom 52 side of the internal gear 5.

[0020] As shown in Figure 3, the side washer 16 integrally has multiple contact portions 161 that abut against the end faces 21a of the large diameter portions 21 of each of the multiple planetary gears 2, and an annular plate-shaped portion 162 that connects the multiple contact portions 161 in the circumferential direction. A portion of the contact portions 161 protrudes radially outward from the annular portion 162. The multiple contact portions 161 of the side washer 16 engage with the planetary carrier 3 and rotate integrally with the planetary carrier 3. The fifth bearing 15 is positioned between the side washer 16 and the closing member 6.

[0021] The large-diameter portion 21 of the planetary gear 2 has a helical gear 210 formed on its entire length that meshes with the external teeth 41 of the sun gear 4. The small-diameter portion 22 has a meshing portion 221 that meshes with the internal teeth 511 of the internal gear 5 and a non-meshing portion 222 that does not mesh with the internal teeth 511 of the internal gear 5. The meshing portion 221 has a helical gear 220 formed on its entire length. The non-meshing portion 222 is formed at the end of the small-diameter portion 22 on the large-diameter portion 21 side. That is, the small-diameter portion 22 meshes with the internal teeth 511 of the internal gear 5 in a part of its axial direction, and has a non-meshing portion 222 at the end on the large-diameter portion 21 side that does not mesh with the internal teeth 511 of the internal gear 5. The non-meshing portion 222 includes the center of gravity G of the planetary gear 2.

[0022] Fig. 8(a) shows a cross-section of the large-diameter portion 21 of the planetary gear 2. In Fig. 8(a), the tip circle diameter of the helical gear 210 formed in the large-diameter portion 21 of the planetary gear 2 is D 22T , 22B , 22B whereas the root circle diameter is D 1B and the pitch circle diameter is D 1P which are respectively shown. The tip circle diameter D 1T of the helical gear 210 corresponds to the outer diameter of the large-diameter portion 21.

[0023] Fig. 8(c) shows a cross-section of the meshing portion 221 in the small-diameter portion 22 of the planetary gear 2. In Fig. 8(c), the tip circle diameter of the helical gear 220 formed in the small-diameter portion 22 of the planetary gear 2 is D 21T whereas the root circle diameter is D 21B and the pitch circle diameter is D 21P which are respectively shown. The tip circle diameter D 21T of the helical gear 220 corresponds to the outer diameter of the small-diameter portion 22. The tip circle diameter D 21T of the small-diameter portion 22 is smaller than the tip circle diameter D 1T of the large-diameter portion 21, and the root circle diameter D 21B of the small-diameter portion 22 is smaller than the root circle diameter D 1B of the large-diameter portion 21. Also, the pitch circle diameter D 21P of the small-diameter portion 22 is smaller than the pitch circle diameter D 1P of the large-diameter portion 21. In the meshing portion 221, the tip circle diameter D 21T , the root circle diameter D 21B , and the pitch circle diameter D 21P are constant throughout the axial direction.

[0024] Fig. 8(b) shows a cross-section of the non-meshing portion 222 in the small-diameter portion 22 of the planetary gear 2. In Fig. 8(c), the tip circle diameter of the helical gear 220 in the non-meshing portion 222 is D 22T whereas the root circle diameter is D 22B which are respectively shown. The helical gear 220 of the small-diameter portion 22 is also formed in a part of the non-meshing portion 222, but the helical gear 220 in the non-meshing portion 222 has a tip circle diameter D 22T and a root circle diameter D 22BThe tooth height, which is the difference between the two, gradually becomes shorter towards the larger diameter section 21, resulting in an incomplete gear section.

[0025] In this embodiment, the tooth tip diameter D in the meshing portion 221 21T and the tip circle diameter D in the non-meshing portion 222 22T The two are the same, and the root circle diameter D in the non-meshing portion 222 22B The diameter gradually increases towards the larger diameter portion 21. This incomplete gear shape is unavoidable when forming the helical gear 220 on the smaller diameter portion 22, for example by hobbing with a hob cutter, depending on the diameter difference between the larger diameter portion 21 and the smaller diameter portion 22, as well as the diameter of the hob cutter.

[0026] The planetary carrier 3 has a spline fitting portion 31 made up of multiple spline teeth 311 extending in the axial direction. The first shaft 71 is connected to the planetary carrier 3 in a way that prevents relative rotation by spline fitting into the spline fitting portion 31. The planetary carrier 3 also has multiple housing holes 30, each housing a multiple planetary gear 2. In this embodiment, the planetary gear device 1 has five planetary gears 2, and the planetary carrier 3 has five housing holes 30 formed at equal intervals in the circumferential direction around the rotation axis O1.

[0027] Each of the multiple housing holes 30 has a large-diameter arc-shaped hole 301 having an arc-shaped inner surface 301a on which the cutting edge surface 210a of the helical gear 210 in the large-diameter portion 21 of the planetary gear 2 slides, a small-diameter arc-shaped hole 302 having an arc-shaped inner surface 302a on which the cutting edge surface 220a of the helical gear 220 in the small-diameter portion 22 of the planetary gear 2 slides, and a cylindrical hole 303 having an inner surface 303a that surrounds the entire circumference of the non-meshing portion 222, which is a part of the axial direction in the small-diameter portion 22 of the planetary gear 2 that does not mesh with the internal teeth 511 of the internal gear 5.

[0028] As shown in Figure 4A, the large-diameter arc-shaped hole 301 opens inward toward the sun gear 4 within the planetary carrier 3, and the inner surface 301a in the cross-section shown in Figure 4A is arc-shaped with an arc angle of 180° or more. The helical gear 210 in the large-diameter portion 21 of the planetary gear 2 has a portion that protrudes inward toward the planetary carrier 3 from the opening 301b of the large-diameter arc-shaped hole 301 that meshes with the external teeth 41 of the sun gear 4.

[0029] As shown in Figure 4C, the small-diameter arc-shaped hole 302 opens outward toward the cylindrical portion 51 of the internal gear 5 towards the planetary carrier 3, and the inner surface 302a in the cross-section shown in Figure 4C is arc-shaped with an arc angle of 180° or more. The helical gear 220 in the small-diameter portion 22 of the planetary gear 2 has a portion that protrudes outward from the opening 302b of the small-diameter arc-shaped hole 302 towards the planetary carrier 3 and meshes with the internal teeth 511 of the internal gear 5.

[0030] As shown in Figure 4B, the cylindrical bore 303 is a cylindrical bore centered on the rotation axis O2 of the planetary gear 2. The inner diameter D3 of the cylindrical bore 303 is the outer diameter of the tooth tip circle diameter D, which is the outer diameter of the non-meshing portion 222 in the small diameter portion 22 of the planetary gear 2. 22T It is formed to be slightly larger than the inner diameter D3 of the cylindrical bore 303 and the tip circle diameter D of the non-meshing portion 222. 22T The difference between these two values ​​should be 0.5 mm or less, and more specifically, preferably between 0.1 mm and 0.3 mm. The center of gravity G of the planetary gear 2 is located inside the cylindrical bore 303.

[0031] Furthermore, the planetary carrier 3 has a wall portion 32 between the large-diameter arc hole 301 and the small-diameter arc hole 302 that surrounds the entire circumference of the end of the small-diameter portion 22 of the planetary gear 2 on the large-diameter portion 21 side, and a cylindrical hole 303 is formed in this wall portion 32. As shown in Figure 9, the wall portion 32 is formed in an arch shape that protrudes radially outward from the outer circumferential surface 3a of the planetary carrier 3 around the opening 302b of the small-diameter arc hole 302.

[0032] As shown in Figures 1 and 4B, a portion of the wall portion 32 is a small-diameter outer peripheral support portion 33 that supports a portion of the axial direction of the small-diameter portion 22 of the planetary gear 2 from the radial outer peripheral side perpendicular to the rotation axis O1. The small-diameter outer peripheral support portion 33 is provided in a location that receives centrifugal force generated on the planetary gear 2 as it rotates (revolves) around the rotation axis O1. In other words, the small-diameter outer peripheral support portion 33 is provided in a location that intersects a straight line that passes through the center of gravity G of the planetary gear 2 and is perpendicular to the rotation axis O1. In Figure 1, this straight line L is shown as a dashed line. The small-diameter outer peripheral support portion 33 supports the non-meshing portion 222, which is a part of the small-diameter portion 22, from the radial outer peripheral side of the planetary carrier 3 along this straight line L.

[0033] (Operation and Effects of the Embodiment) In the planetary gear system 1 configured as described above, when the vehicle is moving forward, the driving force input from the first shaft 71 is distributed to the second shaft 72 and the third shaft 73 and output. At this time, the large-diameter portion 21 of the planetary gear 2 meshes with the external teeth 41 of the sun gear 4, generating a meshing reaction force, and the meshing portion 221 of the small-diameter portion 22 of the planetary gear 2 meshes with the internal teeth 511 of the internal gear 5, generating a meshing reaction force. In Figures 4A and 4C, these meshing reaction forces are shown as F1 and F2.

[0034] The meshing reaction force F1 received by the large-diameter portion 21 of the planetary gear 2 is in the direction away from the axis of rotation O1, while the meshing reaction force F2 received by the meshing portion 221 of the planetary gear 2 is in the direction toward the axis of rotation O1. The meshing reaction force F1 received by the large-diameter portion 21 of the planetary gear 2 is received by the inner surface 301a of the large-diameter arc hole 301, and the meshing reaction force F2 received by the meshing portion 221 of the planetary gear 2 is received by the inner surface 302a of the small-diameter arc hole 302. As a result, the rotation axis O2 of the planetary gear 2 is kept parallel to the axis of rotation O1.

[0035] Furthermore, during low-torque, steady-state driving at high speeds, such as when a vehicle is traveling at a constant speed on a highway, the centrifugal force generated in the planetary gear 2 due to its revolution may be greater than the meshing reaction force F2 with the internal gear 5. However, in this embodiment, the non-meshing portion 222 of the small-diameter portion 22 of the planetary gear 2 is housed in the cylindrical hole 303 of the planetary carrier 3 and supported by the small-diameter outer peripheral support portion 33. This suppresses the tilting of the rotation axis O2 of the planetary gear 2 with respect to the rotation axis O1 due to the centrifugal force generated in the planetary gear 2.

[0036] Figure 10 is a partial cross-sectional view showing an example of the configuration of a planetary gear unit 1A having a planetary carrier 3A, which is a comparative example that does not have a wall portion 32 and a cylindrical hole 303. Figure 11 is a perspective view of a part of the external appearance of the planetary gear unit 1A. Since the other configurations of the planetary gear unit 1A are the same as those of the above embodiment, the same reference numerals used in the description of the above embodiment are used for the components of the planetary gear unit 1A that are common with the planetary gear unit 1 of the above embodiment, and redundant descriptions are omitted.

[0037] In the planetary gear system 1A of this comparative example, if the centrifugal force generated in the planetary gear 2 by its revolution becomes greater than the meshing reaction force with the internal gear 5, the rotation axis O2 of the planetary gear 2 tilts with respect to the rotation axis O1, and the end of the small diameter portion 22 opposite to the large diameter portion 21 is pressed against the corner portion 302c on the opening 302b side of the inner surface 302a of the small diameter arc hole 302. When the planetary gear 2 rotates in this state, wear of the corner portion 302c is accelerated. Note that in Figure 10, the tilt of the planetary gear 2 is exaggerated for clarity of explanation.

[0038] In contrast, in the planetary gear device 1 according to the above embodiment, a portion of the axial direction of the small-diameter portion 22 of the planetary gear 2 is surrounded by the inner surface 303a of the cylindrical hole 303 and supported by the outer peripheral support portion 33 of the small-diameter portion of the planetary carrier 3. Therefore, the tilt of the planetary gear 2 relative to the planetary carrier 3 caused by the centrifugal force generated by the revolution of the planetary gear 2 is suppressed.

[0039] Furthermore, in the above embodiment, the non-meshing portion 222 of the small-diameter portion 22, which includes the center of gravity G of the planetary gear 2, is supported by the small-diameter portion outer peripheral support portion 33, so that the tilting of the planetary gear 2 caused by centrifugal force can be suppressed more reliably. Moreover, since the small-diameter portion outer peripheral support portion 33 supports the non-meshing portion 222, which is an incomplete gear portion that occurs when the helical gear 220 is cut in the small-diameter portion 22, there is no need to additionally provide the portion supported by the small-diameter portion outer peripheral support portion 33 to the planetary gear 2, and the length of the planetary gear 2 can be suppressed.

[0040] (Note) The present invention has been described above based on embodiments, but these embodiments do not limit the invention as defined in the claims. It should also be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention. Furthermore, the present invention can be modified and implemented as appropriate by omitting some components, or by adding or substituting components, without departing from its spirit. It can also be modified as follows, for example.

[0041] In the above embodiment, the case in which the outer peripheral support portion 33 of the small diameter portion of the planetary carrier 3 supports the non-meshing portion 222 which is the end of the small diameter portion 22 on the side of the large diameter portion 21 was described. However, the embodiment is not limited to this, and for example, a supported portion may be provided at the end of the small diameter portion 22 opposite to the large diameter portion 21, and this supported portion may be supported from the outer peripheral side in the radial direction of the planetary carrier by the outer peripheral support portion of the small diameter portion of the planetary carrier. With this configuration as well, it is possible to suppress the tilting of the planetary gear 2 caused by the centrifugal force generated by the revolution of the planetary gear 2. [Explanation of Symbols]

[0042] 1...Planetary gear system 2...Planetary gear 21...Large diameter section 210...Helical gear 210a...Cutting edge surface 22...Small diameter section 220...Helical gear 220a...Cutting edge surface 221...Interlocking part 222...Non-interlocking part 3...Planetary carrier 30...Containment port 301...Large diameter circular arc hole 301a...Inner surface 302...Small diameter circular arc hole 302a...Inner surface 303...Cylindrical bore 303a...Inner surface 31...Wall section 32...Outer circumference support section for small diameter section 4... Sangia 41... External teeth 5...Internal gear 511...Internal teeth

Claims

1. Multiple planetary gears, each having a large diameter section and a small diameter section aligned in the axial direction, with helical gears formed on their respective outer circumferences, A planetary carrier having multiple housing holes formed for housing each of the aforementioned multiple planetary gears, A sun gear is positioned inside the planetary carrier and has external teeth that mesh with the helical gears formed on the large diameter portions of the plurality of planetary gears, The planetary carrier is disposed on the outside and has an internal gear having internal teeth that mesh with the helical gears formed on the small diameter portion of the plurality of planetary gears, The planetary carrier, the sun gear, and the internal gear are capable of relative rotation about a common axis of rotation. Each of the plurality of housing holes has a large-diameter arc-shaped hole having an arc-shaped inner surface on which the cutting edge surface of the helical gear slides in the large-diameter portion, and a small-diameter arc-shaped hole having an arc-shaped inner surface on which the cutting edge surface of the helical gear slides in the small-diameter portion, The planetary carrier has a small-diameter outer peripheral support portion that supports a part of the axial direction of the small-diameter portion from the radial outer peripheral side perpendicular to the axis of rotation. Planetary gear system.

2. Each of the plurality of receiving holes has a cylindrical hole that accommodates a part of the small diameter portion that is supported by the outer peripheral support portion of the small diameter portion. The planetary gear apparatus according to claim 1.

3. The small diameter portion meshes with the internal teeth of the internal gear in a part of the axial direction. The cylindrical bore is formed to surround the portion of the small diameter that does not engage with the internal teeth of the internal gear. The planetary gear apparatus according to claim 2.

4. The small diameter portion has a non-meshing portion at its end on the large diameter side that does not mesh with the internal teeth of the internal gear. The outer peripheral support portion of the small diameter portion supports the non-engaging portion. The planetary gear apparatus according to claim 1.

5. The respective centers of gravity of the multiple planetary gears are included in the non-meshing portion. The planetary gear apparatus according to claim 4.

6. The planetary carrier has a wall portion between the large-diameter arc hole and the small-diameter arc hole that surrounds the outer circumference of the end portion on the large-diameter side of the small-diameter portion. The outer peripheral support portion of the small diameter portion is formed on the wall portion. A planetary gear system according to any one of claims 1 to 5.

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