Planetary gear mechanism and planetary gear device equipped with same

Abstract

Provided are: a planetary gear mechanism which makes it possible to firmly fix a carrier and a pin while suppressing extension in the axial direction; and a planetary gear device equipped with said planetary gear mechanism. A planetary gear device (1A) comprises: an internal gear element (6) that has internal teeth (6c) formed on the inner side of a circumferential wall (6b) which protrudes in the axial direction from a partition wall (6a); and a carrier (4) in which a planetary gear (3) meshing with the internal teeth (6c) of the internal gear element (6) is rotatably supported by a pin (5). The internal gear element (6) is provided with a carrier accommodation recess (n1) that is formed in the partition wall (6a) in a manner accommodating a pin support portion (4b) of the carrier (4). The pin support portion (4b) is disposed in the carrier accommodation recess (n1).

Description

Planetary gear mechanism and planetary gear device including the planetary gear mechanism

[0001] The present invention relates to a planetary gear mechanism and a planetary gear device including the planetary gear mechanism. This application claims the benefit of priority of Japanese Patent Application No. 2024-231228 filed on December 26, 2024, the content of which is incorporated herein by reference.

[0002] In a planetary gear device including a planetary gear mechanism, it is common for the planetary gear to rotate by pins (pinion shafts) provided on a carrier (for example, see Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2018-204613

[0004] However, when the pins are not properly fixed to the carrier, there is a risk that the pins will fall due to the meshing reaction force received from the planetary gear. Such pin collapse causes the planetary gear to not properly mesh with the mating gear, resulting in a decrease in power transmission efficiency or the generation of abnormal noise.

[0005] In contrast, it is conceivable to more firmly fix the pins by increasing the press-fitting allowance (press-fitting length) between the pins press-fitted to the carrier and the carrier.

[0006] However, when increasing the press-fitting allowance of the pins, the conventional planetary gear mechanism has a problem that the axial length of the planetary gear mechanism increases.

[0007] An object of the present invention is to provide a planetary gear mechanism and a planetary gear device including the planetary gear mechanism that can firmly fix the carrier and the pins while suppressing elongation in the axial direction.

[0008] (1) The planetary gear mechanism according to the present invention comprises an internal gear element having internal teeth formed on the inside of a circumferential wall that protrudes axially from a partition wall, and a carrier in which a planetary gear that meshes with the internal teeth of the internal gear element is rotatably supported by pins, wherein the internal gear element has a carrier housing recess in the partition wall that accommodates one of the two pin support portions of the carrier, and one of the two pin support portions is located in the carrier housing recess.

[0009] (2) In the planetary gear mechanism described in (1) above, the internal gear element is provided with an internal gear element side protrusion in the carrier housing recess that forms the carrier housing recess into an annular carrier housing recess, the carrier is provided with an internal gear element housing recess in one of the two pin support portions that accommodates the internal gear element side protrusion, and a bearing is provided between the internal gear element side protrusion of the internal gear element and the internal gear element housing recess of the carrier that rotatably supports the internal gear element and the carrier.

[0010] (3) In the planetary gear mechanism described in (1) above, the internal gear element is provided with an internal gear element side projection in the carrier housing recess that forms the carrier housing recess into an annular carrier housing recess, and the internal gear element side projection is further provided with a second carrier housing recess, the carrier is provided with a carrier side projection on one of the pin support portions that is housed in the second carrier housing recess, and a bearing is disposed between the second carrier housing recess of the internal gear element and the carrier side projection of the carrier to rotatably support the internal gear element and the carrier.

[0011] (4) In any one of the planetary gear mechanisms described in (1) to (3) above, the planetary gear is a composite planetary gear comprising another planetary gear different from the said planetary gear, which is integrally provided with the said planetary gear, and the other planetary gear meshes with the sun gear and the second internal gear element.

[0012] (5) In any one of the planetary gear mechanisms described in (1) to (4) above, the carrier is provided with a cylindrical wall extending in the axial direction on the other of the two pin support portions, a bearing is provided between the cylindrical wall of the carrier and the shaft connected to the sun gear to rotatably support the carrier and the sun gear, and a bearing is provided between the cylindrical wall of the carrier and the second internal gear element to rotatably support the carrier and the second internal gear element.

[0013] (6) The planetary gear device of the present invention comprises one of the planetary gear mechanisms described in (1) to (5) above.

[0014] According to the present invention, it is possible to provide a planetary gear mechanism and a planetary gear device equipped with the planetary gear mechanism that can firmly fix the carrier and the pin while suppressing axial elongation.

[0015] This is a side view showing a planetary gear device equipped with a planetary gear mechanism according to the first embodiment of the present invention. This is a plan view showing the planetary gear device from the input side when the planetary gear device of Figure 1 is used as a reduction gear. This is a plan view showing the planetary gear device from the output side when the planetary gear device of Figure 1 is used as a reduction gear. This is a cross-sectional view showing the planetary gear device of Figure 3 along the line X-X. This is an enlarged cross-sectional view showing region Y in Figure 4. This is a plan view showing the internal rotating gear element from the input side when the planetary gear device of Figure 1 is used as a reduction gear. This is a side view showing the carrier of the planetary gear device of Figure 1 together with the compound planetary gear. This is a plan view showing the carrier together with the compound planetary gear from the output side when the planetary gear device of Figure 1 is used as a reduction gear. This is a plan view showing the carrier together with the compound planetary gear from the input side when the planetary gear device of Figure 1 is used as a reduction gear. This is a plan view showing the internal fixed gear element from the output side when the planetary gear device of Figure 1 is used as a reduction gear. This is a cross-sectional view of a planetary gear device equipped with a planetary gear mechanism according to a second embodiment of the present invention, taken along the line X-X in Figure 3.

[0016] Hereinafter, with reference to the drawings, several embodiments of the present invention, including planetary gear mechanisms and planetary gear devices equipped with planetary gear mechanisms, will be described.

[0017] Here, "axial direction" refers to the direction in which the axis (central axis) extends, and "circumferential direction" refers to the direction around the axis. Furthermore, "perpendicular direction" refers to the direction perpendicular to the axial direction. In addition, the "perpendicular direction" is also called the "radial direction" when the axis is used as the reference (center). Specifically, when referring to the radial direction, the side closer to the axis is called the "inner radial direction," and the side further from the axis is called the "outer radial direction."

[0018] Figure 1 shows a planetary gear device 1A equipped with a planetary gear mechanism M1 according to a first embodiment of the present invention, viewed from the side. Figure 2 shows the planetary gear device 1A from the input side when it is used as a reduction gear. Figure 3 shows the planetary gear device 1A from the output side when it is used as a reduction gear.

[0019] Furthermore, Figure 4 shows the planetary gear system 1A in the X-X section of Figure 3. Here, the X-X section is a cross-section viewed in a plane that includes the central axis O of the planetary gear system 1A (hereinafter also simply referred to as "axis O").

[0020] 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 comprising a sun gear 2, a plurality of compound planetary gears 3, a carrier 4, a plurality of carrier pins 5 corresponding to each compound planetary gear 3, an internal rotating gear element (internal gear element) 6, and an internal fixed gear element (second internal gear element) 7.

[0021] In the following description, the planetary gear system 1A is equipped with a composite planetary gear 3 as a two-stage gear, and is used as a reduction gear with the sun gear 2 as the input rotation element and the internal tooth fixed gear element 7 as the fixed element, thereby using the internal tooth rotating gear element 6 as the output rotation element. In the planetary gear system 1A, the central axis of the sun gear 2 and the central axis of the internal tooth rotating gear element 6 are both the same as axis O.

[0022] In the planetary gear system 1A, the sun gear 2 is an external gear equipped with external teeth 2a. In this embodiment, a rotating shaft (shaft) 8 is connected to the sun gear 2. In this embodiment, the rotating shaft 8 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 disclosure, the central axis of the rotating shaft 8 is also the same as axis O, along with the central axis of the sun gear 2. The rotation of a motor (not shown) as a power source is input to the rotating shaft 8, for example. In this embodiment, the rotating shaft 8 has a connection hole 8h for connecting, for example, the drive shaft of a motor. In this embodiment, the connection hole 8h penetrates the rotating shaft 8 in the axial direction. The drive shaft of a motor can be connected to the connection hole 8h. As a result, rotation from the power source is input to the sun gear 2 via the rotating shaft 8.

[0023] 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 disclosure, the partition wall 6a is a partition wall that closes the output-side open end of the circumferential wall 6b. The circumferential wall 6b extends annularly in the circumferential direction around the axis O and also extends toward the input side from the partition wall 6a. The internal teeth 6c of the internal gear element 6 mesh with the output-side planetary gear 3b of the composite planetary gear 3, which will be described later.

[0024] The composite planetary gear 3 is rotatably supported by carrier pins 5 provided on the carrier 4. In this disclosure, the central axis of the carrier 4 is also the same as axis O. The carrier pins 5 are arranged circumferentially at intervals around axis O. As a result, the composite 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 device 1A includes four composite planetary gears 3 together with the carrier pins 5. However, the number of composite planetary gears 3 (carrier pins 5) can be two or more.

[0025] 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 disclosure, 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 the input-side pin support portion 4a and the output-side pin support portion 4b, respectively.

[0026] In this embodiment, the composite planetary gear 3 comprises an input-side planetary gear 3a and an output-side planetary gear (planetary gear) 3b that is integrally provided with the input-side planetary gear 3a. In this embodiment, the output-side planetary gear 3b is integrally provided by spline fitting inside the input-side planetary gear 3a. As a result, the input-side planetary gear 3a and the output-side planetary gear 3b can rotate integrally around the carrier pin 5 as a composite planetary gear 3. In this embodiment, the output-side planetary gear 3b is a different planetary gear from the input-side planetary gear 3a. In this embodiment, the output-side planetary gear 3b has fewer teeth and a smaller diameter than the input-side planetary gear 3a. As a result, in this embodiment, the composite planetary gear 3 can function with the input-side planetary gear 3a as the input gear, and the output-side planetary gear 3b as the reduction gear.

[0027] The internal gear fixed gear element 7 comprises a housing 7a and an internal gear 7b fixed inside the housing 7a. In this disclosure, the central axes of the housing 7a and the internal gear 7b are the same as axis O. That is, in this disclosure, the central axis of the internal gear fixed gear element 7 is the same as axis O. In this disclosure, 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.

[0028] In this embodiment, the input planetary gear 3a is an external gear having external teeth 3c1. The input planetary gear 3a can revolve around the sun gear 2 on axis O while rotating on its own axis around the carrier pin 5, by meshing the external teeth 3c1 of the input planetary gear 3a 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 disclosure, the output planetary gear 3b is an external gear having external teeth 3c2. The output planetary gear 3b can revolve around the axis O while rotating on its own axis around the carrier pin 5, together with the input planetary gear 3a, by meshing the external teeth 3c2 of the output planetary gear 3b with the internal teeth 6c of the circumferential wall 6b of the internal rotating gear element 6.

[0029] According to the planetary gear system 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.

[0030] Incidentally, if the carrier pin 5 is not firmly fixed to the carrier 4, for example, the meshing reaction force that the composite planetary gear 3 receives from at least one of the sun gear 2, the internal rotating gear element 6, and the internal fixed gear element 7 may not be an appropriate meshing reaction force, which could cause the carrier pin 5 to tilt relative to the output pin support part 4b with the input pin support part 4a as the pivot point. Such tilting of the carrier pin 5 prevents the composite planetary gear 3 from properly meshing with the surrounding gears, which can reduce the power transmission efficiency of the planetary gear mechanism or contribute to the generation of abnormal noise.

[0031] In contrast, 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 carrier 4, which is one 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.

[0032] Figure 5 shows region Y in Figure 4. As shown in Figure 5, according to the planetary gear device 1A, the output side pin support portion 4b of the carrier 4 is housed in the carrier housing recess n1 formed in the internal gear element 6, which allows the axial length (axial thickness) of the output side pin support portion 4b for press-fitting the output side end 5b of the carrier pin 5 to be made longer (thicker). In other words, even if the axial length of the press-fit hole h2 formed in the output side pin support portion 4b for press-fitting the output side end 5b of the carrier pin 5 is made longer because the output side pin support portion 4b of the carrier 4 is housed in the carrier housing recess n1, the elongation of the axial length of the assembly when the carrier 4 is assembled to the internal gear element 6 can be suppressed. Therefore, with the planetary gear system 1A, the output side pin support portion 4b of the carrier 4 is housed in the carrier housing recess n1, which suppresses the elongation of the axial length of the internal gear element 6, while increasing the axial length (press-fit allowance) ΔC of the output side end 5b of the carrier pin 5 that is press-fitted into the output side pin support portion 4b.

[0033] Therefore, the planetary gear device 1A can provide a planetary gear mechanism M1 and a planetary gear device equipped with the planetary gear mechanism M1 that can firmly fix the carrier 4 and the carrier pin 5 while suppressing axial extension. As a result, the planetary gear device 1A can improve power transmission efficiency and reduce the generation of abnormal noise.

[0034] In particular, in this embodiment, the planetary gear unit 1A is a reduction gear equipped with a reduction mechanism that uses an internal rotating gear element 6 as an output element. In this case, since the internal rotating gear element 6 that meshes with the output planetary gear 3b of the composite planetary gear 3 is a rotating member, it is subjected to a larger load than the input planetary gear 3a. Therefore, as in this embodiment, when the axial length of the output pin support portion 4b that mainly supports the output planetary gear 3b is extended, a larger press-fit allowance for the output end 5b of the carrier pin 5 can be secured. In this case, since the output end 5b of the carrier pin 5 is firmly fixed, the planetary gear unit 1A is effective in preventing the carrier pin 5 from tilting.

[0035] Furthermore, as shown in Figure 4, 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 projects toward the input side from the top surface (the central side top surface F632, described later) 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. In addition, a bearing B1 is arranged radially 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, which rotatably supports the internal gear element 6 and the carrier 4.

[0036] Figure 6 shows an internal gear element 6 viewed from the input side in an axial direction. As shown in Figure 6, an annular carrier housing recess n1 is formed in the partition wall 6a of the internal gear element 6, radially inward from the circumferential wall 6b. In this disclosure, the carrier housing recess n1 is composed of an inner circumferential surface F61 that extends annularly around the entire circumference of the axis O, an outer circumferential surface F62 that extends annularly around the entire circumference of the axis O and is located radially inward from the inner circumferential surface F61, and a top surface F63 that connects the inner circumferential surface F61 and the outer circumferential surface F62 and forms the bottom surface of the carrier housing recess n1. In this disclosure, the outer circumferential surface F62 is composed of the outer circumferential surface of the internal gear element side protrusion 6d. In particular, in this embodiment, the carrier housing recess n1 is composed of a two-stage recess comprising a large-diameter portion n11 that accommodates the large-diameter portion 4b1 of the output-side pin support portion 4b described later, and a large-diameter portion n12 that accommodates the small-diameter portion 4b2 of the output-side pin support portion 4b. Accordingly, in this disclosure, the top surface F63 is composed of an outer-edge top surface F631 that corresponds to the outer edge top surface of the large-diameter portion n11 and extends annularly around the entire circumference of the axis O, and a central top surface F632 that corresponds to the top surface of the small-diameter portion n12 and is located radially inward of the outer-edge top surface F631. Furthermore, in this embodiment, the partition wall 6a has an annular stepped surface F65 formed on the input side of the partition wall 6a, radially outward from the peripheral wall 6b, which extends annularly around the entire circumference of the axis O.

[0037] Figure 7 shows the carrier 4 together with the composite planetary gear 3 from the side. 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. An opening A4 is formed between the connecting wall 4c, exposing a part of the composite planetary gear 3.

[0038] In this embodiment, the output-side pin support portion 4b is composed of a large-diameter portion 4b1 having the same external shape as the input-side pin support portion 4a, and a small-diameter portion 4b2 having a smaller diameter than the large-diameter portion 4b1. The small-diameter portion 4b2 protrudes from the large-diameter portion 4b1 toward the output side. As a result, the output-side pin support portion 4b is axially longer than the input-side pin support portion 4a by the axial length ΔL of the small-diameter portion 4b2, L1. As shown in Figure 5, the small-diameter portion 4b2 of the output-side pin support portion 4b, together with a part of the large-diameter portion 4b1 of the output-side pin support portion 4b, is housed in the carrier housing recess n1 of the internal gear element 6. Therefore, even when the output-side pin support portion 4b is extended from the large-diameter portion 4b1 to the small-diameter portion 4b2 by an axial length ΔL, as in this embodiment, the axial length when the carrier 4 is assembled to the internal gear element 6 is reduced compared to when the output-side pin support portion 4b is not housed in the partition wall 6a of the internal gear element 6.

[0039] Furthermore, Figure 8 shows the carrier 4 together with the composite planetary gear 3 from the output side. As shown in Figure 8, in this embodiment, the internal gear element housing recess n2 of the carrier 4 is composed of an inner circumferential surface F41 that extends annularly around the entire circumference of the axis O, and a top surface F42 that is connected to the inner circumferential surface F41 and forms the bottom wall of the internal gear element housing recess n2. Furthermore, in this embodiment, an output side through hole A2 is formed in the top surface F42. As shown in Figure 5, in this embodiment, the bearing B1 is supported by the top surface F42 that forms the internal gear element housing recess n2 of the carrier 4. In addition, in this disclosure, the bearing B1 is press-fitted into the outer circumferential surface F62 that forms the internal gear element side protrusion 6d of the internal gear element 6 and the inner circumferential surface F41 that forms the internal gear element housing recess n2 of the carrier 4, thereby rotatably supporting the carrier 4 and the internal gear element 6 in the radial direction. This allows the carrier 4 and the internal gear element 6 to rotate relative to each other in the circumferential direction around the axis O.

[0040] In the planetary gear system 1A, the internal gear element housing recess n2 is preferably formed with an output-side through hole A2 on the top surface F42 to facilitate the attachment and detachment of the bearing B1 during maintenance. However, the internal gear element housing recess n2 may also be a recess closed off by the top surface F42 without forming an output-side through hole A2 on the top surface F42.

[0041] Furthermore, in this embodiment, the carrier 4 has a cylindrical wall 4d extending in the axial direction at the input-side pin support portion 4a. Between the cylindrical wall 4d of the carrier 4 and the rotating shaft 8 connected to the sun gear 2, a bearing B2 is arranged to rotatably support the carrier 4 and the rotating shaft 8 in the radial direction, thereby rotatably supporting the carrier 4 and the sun gear 2. In addition, in this embodiment, a bearing B3 is arranged between the cylindrical wall 4d of the carrier 4 and the internal tooth fixed gear element 7 in the radial direction, thereby rotatably supporting the carrier 4 and the internal tooth fixed gear element 7.

[0042] Figure 9 shows the carrier 4 together with the composite planetary gear 3 from the input side. As shown in Figure 9, in this embodiment, an overhang surface F44 is formed on the radially inward side of the cylinder wall 4d, connected to the inner circumferential surface F43 of the cylinder wall 4d. In this disclosure, the input side through hole A1 formed on the inside of the cylinder wall 4d is formed on the radially inward side of the overhang surface F44. Also, as shown in Figure 9, a press-fit hole h1 is formed in the input side pin support portion 4a for press-fitting the input side end 5a of the carrier pin 5. 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 press-fit hole h1.

[0043] As shown in Fig. 5, in the present embodiment, the bearing B2 has an output-side end provided on a contact surface F44 inside the radial direction of the cylindrical wall 4d of the carrier 4 and abuts against a stepped surface F81 provided on the rotating shaft 8. Further, in the present embodiment, the bearing B2 is press-fitted onto the outer peripheral surface F82 of the small-diameter portion of the rotating shaft 8 and the inner peripheral surface F43 of the cylindrical wall 4d, thereby rotatably supporting the carrier 4 and the sun gear 2 in the radial direction. As a result, the sun gear 2 and the carrier 4 can relatively rotate in the circumferential direction around the axis O. In the present embodiment, the bearing B2 is retained against removal by the C-ring 9 by fitting the C-ring 9 into a fitting groove 4g formed in the inner peripheral surface F45 of the cylindrical wall 4d.

[0044] Fig. 10 shows the internal gear fixed gear element 7 as viewed from the output side. As shown in Fig. 10, the housing 7a has a through-hole A7 through which the cylindrical wall 4d of the carrier 4 can pass. In Fig. 10, reference numeral F71 denotes a hole surface forming the through-hole A7. Further, in the present embodiment, the housing 7a has an inner peripheral surface F72 for holding the bearing B4 described later. The housing 7a also has a stepped surface F73 that extends annularly over the entire circumference around the axis O along the inner peripheral surface F72. As shown in Fig. 5, in the present embodiment, the bearing B3 is press-fitted onto the outer peripheral surface F45 of the cylindrical wall 4d of the carrier 4 and the hole surface F71 forming the through-hole A7 of the internal gear fixed gear element 7, thereby rotatably supporting the carrier 4 and the internal gear fixed gear element 7 in the radial direction. As a result, the carrier 4 can relatively rotate in the circumferential direction around the axis O with respect to the internal gear fixed gear element 7.

[0045] Furthermore, as shown in Figure 4, in this embodiment, a bearing B4 is press-fitted between the outer circumferential surface F64 of the circumferential wall 6b of the internal gear rotating element 6 and the inner circumferential surface F72 of the internal fixed gear element 7 (housing 7a). As a result, the bearing B4 rotatably supports the internal gear rotating element 6 and the internal fixed gear element 7 in the radial direction. This allows the internal gear rotating element 6 to rotate relative to the internal fixed gear element 7 in the circumferential direction around the axis O. In this embodiment, the input end of the bearing B4 is supported by the stepped surface F73 of the internal fixed gear element 7 (housing 7a). Also in this embodiment, the bearing B4 is housed between the housing 7a and the cover 10, which is attached to the housing 7a of the internal fixed gear element 7. In this embodiment, the cover 10 is an annular cover extending in an annular manner around the entire circumference of the axis O. In this embodiment, a stepped surface F10 is formed radially inward at the input end of the cover 10. In this embodiment, the output end of bearing B4 abuts against the stepped surface F65 of the internal gear element 6 (partition wall 6a) and the stepped surface F10 of the cover 10.

[0046] In this embodiment, a bearing B1 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, rotatably supporting the internal gear element 6 and the carrier 4. In this case, the carrier pin 5 is supported radially inward by the internal gear element 6 via the output side planetary gear 3b of the composite planetary gear 3, while the carrier 4 is supported radially outward by the internal gear element 6 via the bearing B1. In addition, in this embodiment, the internal gear element 6 is supported radially by the internal fixed gear element 7 via the bearing B4. Therefore, in this case, tilting of the carrier pin 5, particularly tilting of the carrier pin 5 caused by a radial external force applied to the output side end 5b of the carrier pin 5, can be suppressed. In particular, according to this embodiment, by using the internal gear element side protrusion 6d of the internal gear element 6, centering (alignment) around the axis O can be easily performed when assembling the carrier 4 and the internal gear element 6.

[0047] Also, in the present embodiment, the input-side planetary gear 3a of the compound planetary gear 3 meshes with the sun gear 2 and the internally-toothed fixed gear element 7. In this case, the carrier pin 5 is supported radially inward by the internally-toothed fixed gear element 7 via the input-side planetary gear 3a of the compound planetary gear 3 and, at the same time, is supported radially outward by the sun gear 2 via the input-side planetary gear 3a of the compound planetary gear 3. Therefore, in this case, it is possible to suppress the tilting of the carrier pin 5, particularly the tilting of the carrier pin 5 that may occur when a radial external force is applied to the input-side end portion 5a of the carrier pin 5.

[0048] Also, in the present embodiment, a bearing B2 is disposed between the cylindrical wall 4d of the carrier 4 and the rotating shaft member 8. Further, in the present embodiment, a bearing B3 is disposed between the cylindrical wall 4d of the carrier 4 and the internally-toothed fixed gear element 7. In this case, the cylindrical wall 4d of the carrier 4 is supported radially inward by the internally-toothed fixed gear element 7 via the bearing B3 and, at the same time, is supported radially outward by the rotating shaft member 8 via the bearing B2. Therefore, in this case, it is possible to suppress the tilting of the carrier 4, particularly the tilting of the carrier 4 that may occur when a radial external force is applied to the input-side pin support portion 4a of the carrier 4, and, consequently, the tilting of the carrier pin 5 that may occur when a radial external force is applied to the input-side end portion 5a of the carrier pin 5.

[0049] On the other hand, in the present embodiment, a bearing B4 is disposed between the internally-toothed rotating gear element 6 and the internally-toothed fixed gear element 7. Further, in the present embodiment, a bearing B1 is disposed between the internally-toothed rotating gear element 6 and the output-side pin support portion 4b of the carrier 4. In this case, the internally-toothed rotating gear element 6 is supported radially inward by the internally-toothed fixed gear element 7 via the bearing B4, and further, the output-side pin support portion 4b of the carrier 4 is supported radially outward by the internally-toothed rotating gear element 6 via the bearing B1. Therefore, in this case, it is possible to suppress the tilting of the carrier 4, particularly the tilting of the carrier 4 that may occur when a radial external force is applied to the output-side pin support portion 4b of the carrier 4, and, consequently, the tilting of the carrier pin 5 that may occur when a radial external force is applied to the output-side end portion 5b of the carrier pin 5.

[0050] In particular, in this embodiment, the input-side pin support portion 4a of the carrier 4 is radially supported by bearings B2 and B3 on the rotating shaft 8 and internal fixed gear element 7 of the sun gear 2, respectively, while the output-side pin support portion 4b of the carrier 4 is radially supported by bearings B4 and B1 on the internal fixed gear element 7 via the internal rotating gear element 6. Therefore, according to this embodiment, both the input-side pin support portion 4a and the output-side pin support portion 4b of the carrier 4 are supported radially, resulting in a double-supported structure, which allows the central axis of the carrier 4 to coincide with axis O. Consequently, according to this embodiment, the inclination of the carrier 4 with respect to axis O can be efficiently suppressed.

[0051] Figure 11 shows a planetary gear assembly 1B equipped with a planetary gear mechanism M2 according to a second embodiment of the present invention, in a cross-sectional view corresponding to the X-X line in Figure 3. The planetary gear assembly 1B is a modified example of the planetary gear assembly 1A. Therefore, parts that are substantially the same as those in the planetary gear assembly 1A are given the same reference numerals, and their descriptions are omitted.

[0052] In the planetary gear system 1B, the internal gear element 6, similar to the planetary gear system 1A, has an internal gear element side projection 6d in the carrier housing recess n1, which forms the carrier housing recess n1 into an annular carrier housing recess n1. In addition, the planetary gear system 1B further has a second carrier housing recess n3 in the internal gear element side projection 6d. On the other hand, in this embodiment, the carrier 4 has a carrier side projection 4p in the output side pin support portion 4b that is housed in the second carrier housing recess n3. In the planetary gear system 1B, a bearing B5 is arranged between the second carrier housing recess n3 of the internal gear element 6 and the carrier side projection 4p of the carrier 4, which rotatably supports the internal gear element 6 and the carrier 4.

[0053] In this embodiment, the carrier-side protrusion 4p provided on the carrier 4 protrudes toward the output side from the internal gear element housing recess n2 formed in the output-side pin support portion 4b. The carrier-side protrusion 4p of the carrier 4 is housed in the internal gear element housing recess n2 of the output-side pin support portion 4b as part of the output-side pin support portion 4b of the carrier 4, and at the same time, it is housed in the second carrier housing recess n3 of the internal gear element 6. The bearing B5 is press-fitted between the inner circumferential surface F66 of the internal gear element 6 that forms the second carrier housing recess n3 and the outer circumferential surface F47 of the carrier-side protrusion 4p on the carrier 4, thereby rotatably supporting the internal gear element 6 and the carrier 4 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.

[0054] In the planetary gear system 1B, a bearing B5 is positioned between the second carrier housing recess n3 of the internal gear rotating element 6 and the carrier-side protrusion 4p of the carrier 4, rotatably supporting the internal gear rotating element 6 and the carrier 4. In this case, the carrier pin 5 is supported radially inward by the internal gear rotating element 6 via the output-side planetary gear 3b of the composite planetary gear 3, and at the same time, the carrier 4 is supported radially inward by the internal gear rotating element 6 via the bearing B5, thereby centering it to the axis O. In addition, in this embodiment, the internal gear rotating element 6 is supported radially by the internal fixed gear element 7 via the bearing B4. Therefore, in this case, tilting of the carrier pin 5, particularly tilting of the carrier pin 5 that may occur when a radial external force is applied to the output-side end 5b of the carrier pin 5, can be suppressed. In particular, according to this embodiment, by using the carrier-side protrusion 4p of the carrier 4, centering around the axis O can be easily performed when assembling the carrier 4 and the internal gear rotating element 6.

[0055] Furthermore, in this embodiment, a bearing B4 is positioned between the internal rotating gear element 6 and the internal fixed gear element 7. In addition, in this embodiment, a bearing B5 is positioned between the internal rotating gear element 6 and the output side pin support portion 4b of the carrier 4. In this case, the internal rotating gear element 6 is supported radially inward from the internal fixed gear element 7 via the bearing B4, and furthermore, the output side pin support portion 4b of the carrier 4 is supported radially inward from the internal rotating gear element 6 via the bearing B5. Therefore, in this case, it is possible to suppress the tilting of the carrier 4, in particular the tilting of the carrier 4 which can occur when a radial external force is applied to the output side pin support portion 4b of the carrier 4, and consequently, the tilting of the carrier pin 5 which can occur when a radial external force is applied to the output side end portion 5b of the carrier pin 5.

[0056] Furthermore, in this embodiment as well, the input-side pin support portion 4a of the carrier 4 is radially supported by bearings B2 and B3 on the rotating shaft 8 and internal fixed gear element 7 of the sun gear 2, respectively, while the output-side pin support portion 4b of the carrier 4 is radially supported by bearings B4 and B5 on the internal fixed gear element 7 via the internal rotating gear element 6. Therefore, according to this embodiment, both the input-side pin support portion 4a and the output-side pin support portion 4b of the carrier 4 are supported radially, resulting in a double-supported structure, which allows the central axis of the carrier 4 to coincide with axis O. Consequently, according to this embodiment, the inclination of the carrier 4 with respect to axis O can be efficiently suppressed.

[0057] 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, M2) 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 from single gears may be used instead of the compound planetary gear 3. Also, although bearings B1 to B5 have been described as rolling bearings, they may be sliding bearings. Furthermore, in a planetary gear device equipped with the planetary gear mechanism according to this embodiment, the internal gear 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.

[0058] 1A: Planetary gear system (first embodiment), 2a: External teeth, 1B: Planetary gear system (second embodiment), O: Axis (central axis of the planetary gear system), 2: Sun gear, 3: Compound planetary gear, 3a: Input side planetary gear (other planetary gear), 3b: Output side planetary gear (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, 4g: Fitting groove, 4p: Carrier side protrusion, 5: Carrier pin (pin), 5a: Input side end, 5b: Output side end, 6: Internal gear rotating gear element (internal gear element), 6a: Partition wall, 6b: Circumferential wall, 6c: Internal tooth, 6d: Protrusion on the internal tooth rotating gear element side (protrusion on the internal tooth gear element side), 7: Internal tooth fixed gear element (second internal tooth gear element), 7a: Housing, 7b: Internal tooth gear, 7c: Internal tooth, 8: Rotating shaft (shaft), 8h: Connection hole, 9: C-ring, 10: Cover, A1: Input side through hole, A2: Output side through hole, A7: Through hole, B1: Bearing between carrier and internal tooth rotating gear element, B2: Bearing between sun gear and carrier, B3: Bearing between carrier and internal tooth fixed gear element, B4: Bearing between internal tooth rotating gear element and internal tooth fixed gear element, B5: Bearing between carrier and internal tooth rotating gear element, F10: Stepped surface of cover, F41: Inner circumferential surface of recess housing internal tooth rotating gear element, F42: Top surface of recess housing internal tooth rotating gear element, F43: Inner circumferential surface of the cylinder wall, F44: Protruding surface, F45: Outer circumferential surface of the cylinder wall, F46: Outer circumferential surface of the carrier-side protrusion, F61: Inner circumferential surface of the carrier housing recess, F62: Outer circumferential surface of the internal gear element-side protrusion, F63: Top surface of the carrier housing recess, F631: Outer edge-side top surface, F632;F64: Center side top surface, F65: Outer surface of the peripheral wall, F66: Stepped surface of the partition wall, F71: Inner surface of the internal gear element, F72: Hole surface, F73: Inner surface of the housing, F81: Stepped surface, F82: Outer surface of the small diameter portion of the rotating shaft, h1: Press-fit hole, h2: Press-fit hole, M1: Planetary gear mechanism (first embodiment), M2: Planetary gear mechanism (second embodiment), n1: Carrier housing recess, n11: Large diameter portion of the carrier housing recess, n12: Small diameter portion of the carrier housing recess, n2: Internal gear element housing recess (internal gear element housing recess), n3: Second carrier housing recess;

Claims

1. A planetary gear mechanism comprising: an internal gear element having internal teeth formed on the inside of a circumferential wall protruding axially from a partition wall; and a carrier on which planetary gears that mesh with the internal teeth of the internal gear element are rotatably supported by pins, wherein the internal gear element has a carrier housing recess in the partition wall for housing one of the two pin support portions of the carrier, and one of the two pin support portions is positioned in the carrier housing recess.

2. The planetary gear mechanism according to claim 1, wherein the internal gear element has an internal gear element side protrusion in the carrier housing recess that forms the carrier housing recess into an annular carrier housing recess, the carrier has an internal gear element housing recess in one of the two pin support portions that accommodates the internal gear element side protrusion, and further, a bearing is disposed between the internal gear element side protrusion of the internal gear element and the internal gear element housing recess of the carrier to rotatably support the internal gear element and the carrier.

3. The internal gear element is provided with an internal gear element-side projection in the carrier housing recess that forms the carrier housing recess into an annular carrier housing recess, and the internal gear element-side projection is further provided with a second carrier housing recess, the carrier is provided with a carrier-side projection on one of the pin support portions that is housed in the second carrier housing recess, and a bearing is disposed between the second carrier housing recess of the internal gear element and the carrier-side projection of the carrier to rotatably support the internal gear element and the carrier, the planetary gear mechanism according to claim 1.

4. The planetary gear mechanism according to claim 1, wherein the planetary gear is a composite planetary gear comprising another planetary gear different from the planetary gear provided integrally with the planetary gear, and the other planetary gear meshes with the sun gear and the second internal gear element.

5. The planetary gear mechanism according to claim 1, wherein the carrier has a cylindrical wall extending in the axial direction on the other of the two pin support portions, a bearing is disposed between the cylindrical wall of the carrier and a shaft connected to the sun gear to rotatably support the carrier and the sun gear, and a bearing is disposed between the cylindrical wall of the carrier and a second internal gear element to rotatably support the carrier and the second internal gear element.

6. A planetary gear apparatus comprising the planetary gear mechanism described in any one of claims 1 to 5.

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